8 month old cockapoo. Fed up with him eating random crap.

HELP! 8 month old cockapoo since very young has been fond of eating random (non food items) plush toys, sticks, wee wee pads , plastic, flowers, leaves. I have constantly, to the very best of my ability have “puppy proof” all common areas in the house but holy crap i do not know where he finds them. He does not follow when i say “out” or when I try to trade with him because he has resource guarded before. I’m afraid he’ll cause himself gastric issues which he had already been showing signs of 😩

What else can i do?!?! Any and all tips would be greatly appreciated!