Definitely donate them! My DH and I frequent the thrift stores every week. In one of the stores the manager was emptying the book and magazine shelves and tossing them into a grocery cart. I asked what he was going to do with them and he said they are going into the trash. I asked if he recycled them and he said no. So, I would suggest you find out if the place you donate them to discards them periodically. If so, find out when and go back and retrieve them and take them to another thrift store. I just hate to see anything go to waste, especially anything related to quilting.