You can use the more worn sheets for backing of quilt tops that are a bit thin. You know, where you've used fabric that isn't "top drawer", and shows a bit thin. Just baste the sheet onto the quilt top, and as you quilt it, remove the basting. It adds strength to the quilt top, and no one will ever see it. Just don't use a sheet that's "pilling". I'm afraid that one's for rags or practice.