I've always kept the ribbons when I've sold a quilt. I usually provide a written list of any awards the quilt has won, as well as any shows it was in, and a copy of my quilting CV, (resume). If it was published I give the buyer a copy of the magazine it was in. (If you get a quilt published, buy at least a half dozen issues of the magazine).
I had an experience with my only Best of Show quilt 20 years ago. I put it in a local quilt shop's annual show and sale and put what seemed like a crazy high price on it, thinking no one would pay that much. Someone did. I was shocked. Fortunately I had some great pictures of it so I framed my ribbon with the photo. I still have it hanging in my studio to remind myself to make sure I'm OK with selling something. I won't make that mistake again.