In Harper Lee's novel, To Kill a Mockingbird, Scout comes across a stick of gum in an old oak tree near the Radley house. Jem finds her with the gum and scolds her for chewing gum that she found. After telling Jem where she found it, Jem tells Scout to "spit it out right now." Scout tells Jem that it is okay touching the trees near the Radley house given he touched the porch once. Jem tells her that it is a different situation.
A few days later, Jem visits the tree with Scout. This time, they find "a small box patchworked with bits of tinfoil collected from chewing-gum wrappers." The box contained two Indian Head pennies. Scout and Jem decide to keep them and ask around at school if they belong to anyone.
The hole in the tree, eventually, ends up containing two soap figures, a medal, more gum, and a pocket watch. The children decide to write a thank you letter to the person putting the gifts into the tree.
When Jem begins the letter, Scout asks him why he wrote "Dear Mister" on the note. Scout thinks that the person who put the gifts into the tree for them is Miss Maudie. After the note is left, the children come back to find a response. Instead, they find that the hole in the tree has been cemented over. Mr. Radley admits to cementing the tree hole because the tree is sick.