What's the best tree to plant and where can I get one?

I can't stop crying about the loss of Dame Jane Goodall. I already donated all I could and let my family know my Christmas list this year is her website. I need to do something physical, though.

I have a house with a yard (for now, we're planning to sell it next year) but I'd love to plant a tree. I'm overwhelmed with work right now and don't have the time to research this till after Christmas but I desperately want to do something more nowish.

If anyone happens to know the best local place to get a local tree that I could plant in my yard, I'd greatly appreciate the help.