The trees at the edge of the Radleys' property are live oaks. They have protruding roots that extend into the road alongside the yard.
In one of the oaks is a knot hole. The first time Scout notices it is because of the silvery paper; she finds Double Mint chewing gum—two fresh but unwrapped sticks—inside.
In the days that follow, after Scout again sees a silvery gum wrapper, the children find other treasures in the hole. In a tiny velvet box covered with more foil, there are two bright but very old pennies. After that, Jem and Scout find twine, two carved figurines that resemble them, more gum, an old school medal, a pocket watch, a chain, and a small knife.
They decide to write a formal thank-you note and leave it in the hole, but when they go to place it there, they find the hole has been filled in with cement.
Along the side adjoining the school yard and the Radleys' chicken coops, there are also pecan trees. A long-standing myth has it that the nuts are poisonous. Jem thinks at first that the knot hole gifts are poisonous, but after the gum fails to kill Scout, he becomes enamored with the gifts, especially the watch. He stops obsessing about the poison trees.