I have a hint to 'test' fabrics for OBW/Stack n Whack type quilts to see what you will get before you ever cut into the fabric.
I have 2, 3"x5" locker mirrors duct taped together along one short edge. Then open into a V-shape and then glide it over your fabric to see what a wonderful array of designs appear. I love using it just to look at fabrics, it is awesome and you can spend a lot of time just 'looking' at your fabric. The mirrors are portable enough to tuck in your purse when you go shopping. You can also use regular mirrors in the same size if you can not find the locker mirrors.
Check it out to see what you find-in your fabrics.