It is an old pattern, "Snakes in the Hollow", I believe. It's a fan variation with fans in opposite corners of the basic block. Sometimes the block has one large fan and the opposite fan is small. The blocks can be set in various twisty ways or in the setting like yours. I found an unfinished quilt in an antique shop that had large and small balls made of fans. It took me a long time to realize that it was a different set of "Snakes in the Hollow"