The goal of this post is to discuss weirwoods/old gods/greenseers speaking to people "through the trees".

We get two instances where Bran is told by characters about how the trees are used by the "gods" in order to speak to people. And while this primarily foreshadows his future as powerful greenseer, I thought it would be interesting to look at different examples in the series that mirror how Bloodraven/Osha explain to Bran how the trees talk/whisper.

The Whispers of the Trees

Note: I am going to use trees/"old gods"/greenseer pretty interchangeably with regards to who is doing the actual "whispering/talking".

Example #1 (Osha)

I tried to parse it down as much as possible, but the premise is clear. The "old gods" speak through the trees (wind/leaves, etc.)

A faint wind sighed through the godswood and the red leaves stirred and whispered. Summer bared his teeth. "You hear them, boy?" a voice asked.

...

"They are my gods too," Osha said. "Beyond the Wall, they are the only gods." ...

"No, stay," Bran commanded her. "Tell me what you meant, about hearing the gods."

Osha studied him. "You asked them and they're answering. Open your ears, listen, you'll hear."

Bran listened. "It's only the wind," he said after a moment, uncertain. "The leaves are rustling."

"Who do you think sends the wind, if not the gods?" She seated herself across the pool from him, clinking faintly as she moved. ... "They see you, boy. They hear you talking. That rustling, that's them talking back."

"What are they saying?"

"They're sad. Your lord brother will get no help from them, not where he's going. The old gods have no power in the south. The weirwoods there were all cut down, thousands of years ago. How can they watch your brother when they have no eyes?"

Bran had not thought of that. It frightened him. If even the gods could not help his brother, what hope was there? Maybe Osha wasn't hearing them right. He cocked his head and tried to listen again. He thought he could hear the sadness now, but nothing more than that

Example #2 (Bloodraven)

Once Bran reaches Bloodraven's cave, Bloodraven explains this about Bran trying to reach Ned (in the past).

"But," said Bran, "he heard me."

"He heard a whisper on the wind, a rustling amongst the leaves. You cannot speak to him, try as you might. I know. I have my own ghosts, Bran. A brother that I loved, a brother that I hated, a woman I desired. Through the trees, I see them still, but no word of mine has ever reached them. The past remains the past. We can learn from it, but we cannot change it."

If interested: Accessible Weirwood/Heart Trees & A Thousand Eyes and One: Informants & Disguises of Bloodraven

Other Potential Options

So with the above two examples in mind lets get to some potential examples where someone was near a weirwood/heart tree and the "old gods" might have answered their prayer, etc.

Obviously a good amount of these examples can likely be seen as world buildling/scene setting and aren't actual contact from the Old Gods. That said even some of those are worded in a way that seems to say "we are here" even if the character doesn't notice.

The Appearance of the Others

A cold wind was blowing out of the north, and it made the trees rustle like living things. All day, Will had felt as though something were watching him,

and:

The woods gave answer: the rustle of leaves, the icy rush of the stream, a distant hoot of a snow owl.

The Others made no sound. -AGOT, Prologue

It should be noted that while the Others make no sound, their language is eerily similar to the sounds listed above (as the the True Tongue, language of the COTF, etc.)

Bran's Coma Dream & Training as a Greenseer

While the leaves don't seem to speak, the weirwood looks at him "knowingly" (so I had to include it).

He saw Winterfell as the eagles see it, the tall towers looking squat and stubby from above, the castle walls just lines in the dirt. He saw Maester Luwin on his balcony, studying the sky through a polished bronze tube and frowning as he made notes in a book. He saw his brother Robb, taller and stronger than he remembered him, practicing swordplay in the yard with real steel in his hand. He saw Hodor, the simple giant from the stables, carrying an anvil to Mikken's forge, hefting it onto his shoulder as easily as another man might heft a bale of hay. At the heart of the godswood, the great white weirwood brooded over its reflection in the black pool, its leaves rustling in a chill wind. When it felt Bran watching, it lifted its eyes from the still waters and stared back at him knowingly. -AGOT, Bran III

When they stop at the Nightfort:

It grew very quiet in the castle kitchen then. Bran could hear the soft crackle of the flames, the wind stirring the leaves in the night, the creak of the skinny weirwood reaching for the moon. -ASOS, Bran IV

Later while in Bloodraven's Cave:

The moon was a crescent, thin and sharp as the blade of a knife. A pale sun rose and set and rose again. Red leaves whispered in the wind. Dark clouds filled the skies and turned to storms. Lightning flashed and thunder rumbled, and dead men with black hands and bright blue eyes shuffled round a cleft in the hillside but could not enter. Under the hill, the broken boy sat upon a weirwood throne, listening to whispers in the dark as ravens walked up and down his arms. -ADWD, Bran III

and Jojen's thoughts on Bran:

"It is given to a few to drink of that green fountain whilst still in mortal flesh, to hear the whisperings of the leaves and see as the trees see, as the gods see," said Jojen. "Most are not so blessed. The gods gave me only greendreams. My task was to get you here. My part in this is done." -ADWD, Bran III

Arya Stark

Not necessarily a weirwood/heart tree, but due to location (God's Eye) I had to include it.

It was a black night, with a thin sliver of moon appearing and disappearing as the clouds blew past. Silent as a shadow, she told herself as she moved through the trees. In this darkness she dared not run, for fear of tripping on some unseen root or losing her way. On her left Gods Eye lapped calmly against its shores. On her right a wind sighed through the branches, and leaves rustled and stirred. Far off, she heard the howling of wolves. -ACOK, Arya V

If interested: Weird Happenings Around the God's Eye

Later in the Harrenhal Godswood:

For a long moment there was no sound but the wind and the water and the creak of leaf and limb. And then, far far off, beyond the godswood and the haunted towers and the immense stone walls of Harrenhal, from somewhere out in the world, came the long lonely howl of a wolf. Gooseprickles rose on Arya's skin, and for an instant she felt dizzy. Then, so faintly, it seemed as if she heard her father's voice. "When the snows fall and the white winds blow, the lone wolf dies, but the pack survives," he said.

"But there is no pack," she whispered to the weirwood. Bran and Rickon were dead, the Lannisters had Sansa, Jon had gone to the Wall. "I'm not even me now, I'm Nan."

"You are Arya of Winterfell, daughter of the north. You told me you could be strong. You have the wolf blood in you." -ACOK, Arya X

and then while in Braavos we get this as well (which isn't talking to her, but its acknowledgement of someone there):

Except in dreams. She took a breath to quiet the howling in her heart, trying to remember more of what she'd dreamt, but most of it had gone already. There had been blood in it, though, and a full moon overhead, and a tree that watched her as she ran. -TWOW, Mercy

The Ghost of High Heart

"Your brother may be gone," said Thoros. "Your mother as well. I did not see them in the flames. This wedding the old one spoke of, a wedding on the Twins . . . she has her own ways of knowing things, that one. The weirwoods whisper in her ear when she sleeps. If she says your mother is gone to the Twins . . ." -ASOS, Arya VIII

If interested: Comparing Visions: Melisandre and the Ghost of High Heart

Osha

This is a bit speculative, but the old gods could have guided Osha to Skagos:

Osha gazed up at the weirwood, at the red face carved in the pale trunk. "And leave you for the gods?"
"I beg . . ." The maester swallowed. ". . . a . . . a drink of water, and . . . another boon. If you would...

If interested: Everything We Know About Skaagos & Osha's Decision: Taking the Raging Wolf to the Isle of Cannibals

Jon (Horn & Dragonglass & Vision of the Frostfangs)

While on the ranging, its possible that there was some direction to Jon/Ghost with regards to finding the horn/dragonglass:

Closer at hand, it was the trees that ruled. To south and east the wood went on as far as Jon could see, a vast tangle of root and limb painted in a thousand shades of green, with here and there a patch of red where a weirwood shouldered through the pines and sentinels, or a blush of yellow where some broadleafs had begun to turn. When the wind blew, he could hear the creak and groan of branches older than he was. A thousand leaves fluttered, and for a moment the forest seemed a deep green sea, storm-tossed and heaving, eternal and unknowable. -ACOK, Jon IV

...

The trees stood beneath him, warriors armored in bark and leaf, deployed in their silent ranks awaiting the command to storm the hill. Black, they seemed . . . it was only when his torchlight brushed against them that Jon glimpsed a flash of green. Faintly, he heard the sound of water flowing over rocks. Ghost vanished in the underbrush. Jon struggled after him, listening to the call of the brook, to the leaves sighing in the wind. Branches clutched at his cloak, while overhead thick limbs twined together and shut out the stars. -ACOK, Jon IV

and then later:

He sniffed at the bark, smelled wolf and tree and boy, but behind that there were other scents, the rich brown smell of warm earth and the hard grey smell of stone and something else, something terrible. Death, he knew. He was smelling death. He cringed back, his hair bristling, and bared his fangs.

Don't be afraid, I like it in the dark. No one can see you, but you can see them. But first you have to open your eyes. See? Like this. And the tree reached down and touched him.

And suddenly he was back in the mountains, his paws sunk deep in a drift of snow as he stood upon the edge of a great precipice. Before him the Skirling Pass opened up into airy emptiness, and a long vee-shaped valley lay spread beneath him like a quilt, awash in all the colors of an autumn afternoon.

A vast blue-white wall plugged one end of the vale, squeezing between the mountains as if it had shouldered them aside, and for a moment he thought he had dreamed himself back to Castle Black. Then he realized he was looking at a river of ice several thousand feet high. Under that glittering cold cliff was a great lake, its deep cobalt waters reflecting the snowcapped peaks that ringed it. There were men down in the valley, he saw now; many men, thousands, a huge host. Some were tearing great holes in the half-frozen ground, while others trained for war. He watched as a swarming mass of riders charged a shield wall, astride horses no larger than ants. The sound of their mock battle was a rustling of steel leaves, drifting faintly on the wind. Their encampment had no plan to it; he saw no ditches, no sharpened stakes, no neat rows of horse lines. Everywhere crude earthen shelters and hide tents sprouted haphazardly, like a pox on the face of the earth. He spied untidy mounds of hay, smelled goats and sheep, horses and pigs, dogs in great profusion. Tendrils of dark smoke rose from a thousand cookfires. -ACOK, Jon VII

Theon (likely talking to Bran)

Bran's storyline stops relatively early compared to other POV characters, so while we don't have confirmation it is, the implications make sense (especially with the expected "showdown at the tree" that should occur early in TWOW):

The night was windless, the snow drifting straight down out of a cold black sky, yet the leaves of the heart tree were rustling his name. "Theon," they seemed to whisper, "Theon."

The old gods, he thought. They know me. They know my name. I was Theon of House Greyjoy. I was a ward of Eddard Stark, a friend and brother to his children. "Please." He fell to his knees. "A sword, that's all I ask. Let me die as Theon, not as Reek." Tears trickled down his cheeks, impossibly warm. "I was ironborn. A son … a son of Pyke, of the islands." -ADWD, A Ghost in Winterfell

and it should be noted that there is no wind here:

She has to understand. She is my sister. He never wanted to do any harm to Bran or Rickon. Reek made him kill those boys, not him Reek but the other one. "I am no kinslayer," he insisted. He told her how he bedded down with Ramsay's bitches, warned her that Winterfell was full of ghosts. "The swords were gone. Four, I think, or five. I don't recall. The stone kings are angry." He was shaking by then, trembling like an autumn leaf. "The heart tree knew my name. The old gods. Theon, I heard them whisper. There was no wind but the leaves were moving. Theon, they said. My name is Theon." It was good to say the name. The more he said it, the less like he was to forget. "You have to know your name," he'd told his sister. "You... you told me you were Esgred, but that was a lie. Your name is Asha." -TWOW, Theon I

Sam's Prayer & Visit to Oldtown

Sam prays to the Old Gods for protection:

He turned back to the weirwood and studied the carved face a moment. It is not the face we saw, he admitted to himself. The tree's not half as big as the one at Whitetree. The red eyes wept blood, and he didn't remember that either. Clumsily, Sam sank to his knees. "Old gods, hear my prayer. The Seven were my father's gods but I said my words to you when I joined the Watch. Help us now. I fear we might be lost. We're hungry too, and so cold. I don't know what gods I believe in now, but . . . please, if you're there, help us. Gilly has a little son." That was all that he could think to say. The dusk was deepening, the leaves of the weirwood rustling softly, waving like a thousand blood-red hands. Whether Jon's gods had heard him or not he could not say. -ASOS, Samwell III

and:

"Fair." The raven landed on his shoulder. "Fair, far, fear." It flapped its wings, and screamed along with Gilly. The wights were almost on her. He heard the dark red leaves of the weirwood rustling, whispering to one another in a tongue he did not know. The starlight itself seemed to stir, and all around them the trees groaned and creaked. Sam Tarly turned the color of curdled milk, and his eyes went wide as plates. Ravens! They were in the weirwood, hundreds of them, thousands, perched on the bone-white branches, peering between the leaves. He saw their beaks open as they screamed, saw them spread their black wings. Shrieking, flapping, they descended on the wights in angry clouds. They swarmed round Chett's face and pecked at his blue eyes, they covered the Sisterman like flies, they plucked gobbets from inside Hake's shattered head. There were so many that when Sam looked up, he could not see the moon.

"Go," said the bird on his shoulder. "Go, go, go." -ASOS, Samwell III

and:

It was cool and dim inside the castle walls. An ancient weirwood filled the yard, as it had since these stones had first been raised. The carved face on its trunk was grown over by the same purple moss that hung heavy from the tree's pale limbs. Half of the branches seemed dead, but elsewhere a few red leaves still rustled, and it was there the ravens liked to perch. The tree was full of them, and there were more in the arched windows overhead, all around the yard. The ground was speckled by their droppings. As they crossed the yard, one flapped overhead and he heard the others quorking to each other. "Archmaester Walgrave has his chambers in the west tower, below the white rookery," Alleras told him. "The white ravens and the black ones quarrel like Dornishmen and Marchers, so they keep them apart." -AFFC, Samwell V

The Crannogmen

Using the "Magics of the Crannogs", the Crannogmen seem to be "in touch" with speaking to the trees.

Bran was almost certain he had never heard this story. "Did he have green dreams like Jojen?"

"No," said Meera, "but he could breathe mud and run on leaves, and change earth to water and water to earth with no more than a whispered word. He could talk to trees and weave words and make castles appear and disappear." -ASOS, Bran II

and:

Their song and music was said to be as beautiful as they were, but what they sang of is not remembered save in small fragments handed down from ancient days. Maester Childer's Winter's Kings, or the Legends and Lineages of the Starks of Winterfell contains a part of a ballad alleged to tell of the time Brandon the Builder sought the aid of the children while raising the Wall. He was taken to a secret place to meet with them, but could not at first understand their speech, which was described as sounding like the song of stones in a brook, or the wind through leaves, or the rain upon the water. The manner in which Brandon learned to comprehend the speech of the children is a tale in itself, and not worth repeating here. But it seems clear that their speech originated, or drew inspiration from, the sounds they heard every day. - TWOIAF, Ancient History: The Dawn Age

Sansa in the Red Keep

There was something wild about a godswood; even here, in the heart of the castle at the heart of the city, you could feel the old gods watching with a thousand unseen eyes.

and in what is one of the best subtle moments of the series Dontos thinks the godswood is actually the only place someone isn't listening:

You must come here, to the godswood. As often as you can. This is the safest place. The only safe place. Nowhere else. Not in your chambers nor mine nor on the steps nor in the yard, even if it seems we are alone. The stones have ears in the Red Keep, and only here may we talk freely.

Likely Wordbuilding

The next few I doubt that most of these are involvement from the old gods, but still worded beautifully nonetheless:

Mormont's Ranging

A gust of wind sent wet leaves flapping round them like a flock of dead birds. The haunted forest, Jon thought ruefully. The drowned forest, more like it. -ACOK, Jon III

Names Said by Ravens in the Series

The Riverrun Godswood

The shortest way to the central keep where her father lay dying was through the godswood, with its grass and wildflowers and thick stands of elm and redwood. A wealth of rustling leaves still clung to the branches of the trees, all ignorant of the word the white raven had brought to Riverrun a fortnight past. Autumn had come, the Conclave had declared, but the gods had not seen fit to tell the winds and woods as yet. -ACOK, Catelyn I

If interested: White Wings, Dark Words

Ned's Visit to the King's Landing Godswood

While Ned is waiting for Cersei to arrive:

How long he waited in the quiet of the godswood, he could not say. It was peaceful here. The thick walls shut out the clamor of the castle, and he could hear birds singing, the murmur of crickets, leaves rustling in a gentle wind. The heart tree was an oak, brown and faceless, yet Ned Stark still felt the presence of his gods. His leg did not seem to hurt so much. -AGOT, Eddard XII

Asha at Deepwood Motte

I cannot go home, she thought, but I dare not stay here much longer. The quiet of the woods unnerved her. Asha had spent her life on islands and on ships. The sea was never silent. The sound of the waves washing against a rocky shore was in her blood, but there were no waves at Deepwood Motte … only the trees, the endless trees, soldier pines and sentinels, beech and ash and ancient oaks, chestnut trees and ironwoods and firs. The sound they made was softer than the sea, and she heard it only when the wind was blowing; then the sighing seemed to come from all around her, as if the trees were whispering to one another in some language that she could not understand. -ADWD, The Wayward Bride

As I mentioned earlier many of these are likely GRRM just setting a scene/world building, but even in those he does an amazing job of making it as though there is something going on, for instance:

TLDR: A list of potential options where a whisper/rustle on the leaves of a weirwood/heart tree could indicate the presence/influence of the old gods/greenseer.