Some quilt patterns that were traditionally done into 2 color quilts are wonderful projects for scrap/crumb pieces. Jacob's Ladder, Bear Claw, Irish Chain even... Piece the scraps together until you get a "piece of fabric" the size that one color of the block would fit on, then cut out the blocks from them. Add the "scrappy blocks" to the second color blocks to complete the quilt top.

You could even just make a simple 4 square pattern or pinwheels. Just use larger squares than you would normally to get more of the "scrap look" into the pattern. The patterns that you end up with can be delightful if you pair your scrap blocks with a dark solid color, such as navy or green.