In To Kill a Mockingbird Boo Radley has been closed up in the Radley house for years and years. Because of this, he attains a mythical status in the minds of Scout and Jem. They add all sorts of terrifying details that make Boo sound like a monster, and it’s clear that the kids are frightened of Boo and his house.
Even when they begin to find items in the knothole of nearby tree (gum, a medal, a pocketwatch, figurines in their likenesses carved from soap), which they assume are gifts from Boo, they still continue to imagine that he is something to be frightened of.
We can only assume that Boo gave them the figurines and other gifts as a sort of acknowledgment of their presence. I think Boo was saying something like, “I know you’re out there and we can be friends.” Whether or not he knows about the awful stories they made up about him is something we can’t know. The fact that he ends up saving their lives at the end of the book indicates that he is a benevolent person.