You can do a sort of faux cathedral windows with them. Cut circles out of the denim and then use a square that just comes to the edge of the circle to mark them. Sew them together with the flaps all on one side. Put a square of fabric on top of the circle as you sew the flaps down over it.
Found a pattern page for you.
http://www.equilters.com/library/jea...gallbaros.html