Boo Radley leaves several gifts for Scout and Jem in the hole in the tree. There they find two pieces of Doublemint chewing gum, two Indian head pennies, and a rusty medal. Boo also gives them soap dolls carved to look like them as well as a broken watch and watch chain.
All these gifts are the reclusive Boo's way of reaching out to the children. The gifts show he knows they are watching and curious about him. He can obviously overhear some of what they say too. For instance, he must hear them discussing whether or not the gifts are for them or possessions belonging to somebody else stashed in the tree. In response, he carves the soap dolls to look like them so they know the presents are theirs. He must know, too, that the children are thrilled to get these gifts, as he keeps on giving them.
The children, however, already have preconceived notions of Boo as the bogeyman, so it is not natural for them to connect the gifts with him.