Aha! You have cracked the code. The keyword is "trust." If the volunteers know you and trust that you aren't bent on mayhem, an arrangement can be made. They don't want these items sent to a landfill; they don't want them as street weapons either. Chat them up, be a regular donor of things they can sell, and always donate a few dollars when they provide you with items they can't put on the shelves. It works.