My mom picked up a flower garden top for me at an antique store with all the edges unfinished. I basted under the raw edges and then took a wide border strip and put it up under each side, basted it together and sewed them on with top stitching. It showed off the edging, which I thought it was prettier than just trimming blocks off straight. This might not be the proper method, but it worked for me.
Wish I had it with me, I'd post it to show you. Good Luck!