I have made flannel quilts using the yellow brick road pattern but any pattern where you aren't making really small pieces or a lot of small halfsquares would be fine. You just don't want tons of seams since they will be a little "thicker". Depending on how warm you want it to be, you don't necessarily have to use a batting in it either. Or just use another piece of flannel in the middle. Oh, when I make flannel quilts I make sure to give the flannel a good washing first because flannel shrinks more and at different rates than other cotton fabrics. If people are sending scraps, most of those will probably already be washed, you may want people to tell you if it is prewashed or not!!