Check out some of the tutorials from Jenny Doan @Missouri Star Quilts, in particular her X and O quilt. She did it as a mystery quilt this past summer & I got all the blocks pieced just from scraps I had from piecing several tops. It's basically a 16 patch with 4patches of cornerd blocks between. I know that's clear as mud, but I'm sure if you watch her you tube video tutorials you'll see how easy it is.
If you still feel like you need some more pops of color, check some LQS for scrap bags that are full of fabrics in odd pieces---a great way to expand your stash color selection with little cost!