Jem tells Scout what really happened when he went back for his pants that night: when he snuck back, he found that someone had mended them and left them on the fence for him to find. What's more, that someone didn't do a very good job of mending the pants, which leads Jem to think that someone knew he was coming back for them, like they read his mind. While they're talking, they pass the knothole, where they find a ball of twine. Scout convinces Jem to leave it there for a few days, in case it's someone's secret hiding place. When the ball is still there days later, they decide to keep it.

Soon after Jem goes through a phase where he tries to walk like an Egyptian, he and Scout find a pair of soap dolls that look just like them in the knothole. This confirms their suspicion that these knothole items are indeed intended to be gifts and that someone is trying to be their friend. Next, they find a watch and knife on a chain that Atticus says would be worth ten dollars if it were still running. Jem tries to fix the watch, but fails. Still, he wears it around, imitating Atticus, who has a real pocket watch that belonged to their grandfather.

When the kids go to place a thank you letter into the knothole, they find that Mr. Nathan Radley has already filled it up with cement. He tells them he did it because the tree is sick, but Jem asks Atticus, and he says the tree isn't sick at all. Later, Scout finds Jem crying and doesn't understand why. It's implied that he's crying because he realized that Boo was giving them the gifts and that Nathan tried to stop him.

Personification

One example of this would be the pants sitting on the fence "like they were expectin'" Jem.

Symbols

Gifts. Traditionally, gifts are symbols of one's affection or appreciation for their recipient. In the case of the gifts left for Jem and Scout in the knothole, they're communiques meant, most likely, to build trust between Boo and the Finch children and prove to them that there's no reason to be afraid of him. However, because the kids are forced to infer who left these gifts for them, their true intent is the subject of some speculation.

Jem's Pocket Watch. Unlike Atticus' pocket watch, which is a symbol of time and social status, Jem's pocket watch is a symbol of his respect for his father, whom he tries to emulate by carrying the watch and chain he finds in the knothole. It's also a symbol of their burgeoning friendship with Boo Radley.

The Knothole. The knothole is a medium of communication and, thus, symbolizes the connection that Boo tries to establish with the Finch children. His gifts represent his affection for Scout and Jem. When the knothole is cemented up, that line of communication closes, symbolizing the divide between Boo and the other characters in the novel.