I thought it was a Bicentennial quilt, and I was very close. This double-knit polyester quilt from Texas has been a little bit of a mystery since I bought it last year. I couldn't find the block pattern anywhere, and I've asked around. When I posted it as a unknown pattern in my blog, "Why?" I mentioned that I'd love to know if anyone knew the name of the block.
Several attempts to find the pattern in Barbara Brackman's Encyclopedia of Pieced Quilt Patterns came up empty, but I admit I'm not always great at finding patterns in the book. Fortunately, hand quilter extraordinaire Tim Latimer found it. The block is called Grandmother's Fan, Brackman # 4096, from Progressive Farmer/Johnson, 1977. It's at the very end of the book, in the miscellaneous section under "with curves" - a small category with just six other block designs.
Interestingly, the pattern in the book appears to have a seam through the center of the large, almost-square patch. But that section is a single piece in my quilt. My reason for thinking it was a Bicentennial quilt was that it was so similar to the Bicentennial star logo, which also includes simple, streamlined arcs with red, white and blue.
So, mystery solved! Thank you, Tim Latimer.