What can I do to help?Can my son receive a free lawyer to help him being charged with possession of drug paraphenilia.

Northport Village PD. found my son to have a plastic bottle with used needles and residual white powder. He is on probation at this time. My son found the plastic bottle at the edge of someone's property near an elementary school and picked it up because he was going to dispose of it. My son regularly collects things he finds. Especially scrap metal, but I do not doubt he would also pick up something that he thought should not be where it was. I took pictures of things in my yard that is due to go to the scrap yard. I have old receipts showing he brings things to the scrap yard. Can this help establish a behavior associated with picking up other peoples trash? I am planning to write a letter to the judge.