Daughter is giving away her things to her classmates, what should I do?

My daughter is a second grader. I bought her led pencils and she was giving them away. I asked to her to please only take one pencil to school per day, and even just bought her regular number 2 pencils. It continued to happen. She said a boy in her class keeps asking and taking them from her desk. I talked to the teacher about it and it stopped happening. The school started giving away tokens (small cards with the school's mascot's picture on it), to students who behave and do their work. My daughter received many tokens, she is a good student. When I counted the tokens she began having less tokens each day from what she had before. My daughter even had bragged about earring more tokens. The numbers didn't match. It seems my daughter either giving the tokens away or the kids are grabbing them from her desk. I am not sure. The teacher hasnt been in school due to being sick so my daughter's class has substitute teachers, has for th past two weeks. It doesn't feel right to just let this pass, how do I handle this? Like I said, its either my daughter givig her stuff away or the kids in her class taking stuff from her. When I ask my daughter about it she gets upset and tries to avoid answering me.