One of the prettiest medalion quilts I ever made was called "Vintage Moments" by Marsha McClusky. I just love that pattern! I made 2 in 30's prints and one in batiks. They are all hand quilted and turned out beautifully. It has a feathered star in the center. Try looking on quilterscashe.com for a center block pattern. They have lots of free patterns in different sizes. Many of them would be perfect for a center medalion.