How about some apple cores?
http://www.quilterscache.com/A/ApplecoreBlock.html
I think doing the piecing by hand would be simple. It's a pattern you can do scrappy, or with variations on a color, bands of color, and more! The undulations of the cores make an interesting effect. The one at quilters cache is a little rounded, but they look good with more clamshelled edges too.