Have you ever noticed that when we are handed free fabric the FIRST thing we think of is: Make a bunch of blocks ....
when the reality is:
we probably have ENOUGH blocks and quilt tops ... we need BACKINGS!
I recently got up against the wall with needing the backing for eight quilts ... I make lap robes that measure (usually) 57x70 inches ... and, after all of this time (15+years), I suddenly discovered that if I have four yards of fabric for backing, I can cut it in half, and use one selvedge to selvedge piece for part of the backing and only have to use 1/2 of the other piece to make more than adequate back ... so, what to do with that extra piece (22x2 yards) ... well, cut it in half, cut other fabrics, in great big pieces, put them together, and viola! Another quilt back!
When I get one quilted, I will post a picture to give you an idea of what the backing looks like .... oh, wait! I will go take care of it ... doesn't have to be quilted ... DUH!
Good idea for your dark fabrics ... BACKINGS! <wave>