Who is the Gum and Penny Man?

Today in class, we read part of chapter four, and something weird happened. One day, Scout was walking home from school, and she went past the Radley house. Inside the knothole of a tree in the front yard of the Radley house, Scout found two sticks of gum. She was intrigued by them, so she licked them to see if they were poisoned, which they were not. After concluding that, she stuffed them into her mouth until later when Jem forced her to spit them out. On the last day of school, Scout and Jem found a box in the knothole. They took the box and opened it. Inside, they found two pennies from the the 1900s. Jem ad Scout are now wondering who owns this. They think that it must be an a child because they think adults don't have hiding spots.

There could be many different people who are placing the gum and the box, but I have a few possibilities. First, it could be a random child that has been placing their belongings in the Radley tree. This seems kinda mean that Scout and Jem would happen to be stealing a kid's possessions, but I doubt a random child being the culprit. Second, it could be an animal like a squirrel. After watching some PBS as a child, I learned that squirrels are attracted to shiny objects. Knowing this, it could be a squirrel that finds shiny objects like gum and pennies, but this is something that I think would be too boring for a book. Third, it could be Boo Radley. This is most likely in my opinion, but I do not know why Boo would do this. My predictions are that he is lonely and wants attention from Scout and Jem, or he is just a weird due who likes putting his things in trees. Most likely, the first reason.

We won't know who the gum and penny man is, but we will find out eventually.