I save anything I can get the seams in for a crumb block. A couple of my 4" square blocks have 52-53 different fabrics in them, so I'd say whatever floats my boat on that particular day. I also make doggie beds mostly with odd sized pieces I really can't use and leftover batting scraps that are too small to seam. I keep my crumbs in a storage tote, and I keep strings in a separate tote. Crumb blocks are my favorite block to make.