Recently discovered a fabric called "osnaberg" which is used instead of batting in rag quilts. Layered with denim and flannel or flannel alone, it frays beautifully and is a lot lighter than batting. Joann's carries it. I love making denim/flannel rag quilts. (you cut the osnaberg blocks the same size as the top and bottom blocks)

Some quilt shops carry osnaberg fabric too. I've used it in rag quilts, it's good and less expensive that flannel.