Young children can have difficulty telling the truth. Sometimes it's just an attempt to avoid conflict, punishment or embarrassment. However, it is important to deal with the behavior as soon as possible so that it does not get out of hand.
Talk to your son in depth about the nature of his “borrowing” behaviors. Try to keep your questioning neutral so that he does not resort to lying to avoid punishment. Help him explore what he could do differently in the future. For example, before accepting anything from another child, instruct him to clear it with you first or be sure that the teacher is aware of what is going on. Meet with the teacher about your son’s behavior. It well may help determine a course of action.
If your son doesn't have a hobby, you may want to explore the idea with him. He may find it fascinating and become more focused on his own collection then picking up things at random, or bringing things home that belong to other children. Anything ranging from rocks to baseball cards are a collector's dream, especially for young boys. Let him give it a try; you may be surprised at the change in his focus.
