I spotted this when my dog peed on the plant, so I was motivated not to dwell on it too long. Still, I've never seen the like of it before. I've been searching for corkscrew, spiral, and helical seed pods and haven't come up with anything close. The spirals are only about 3/8" across, so it's a tiny thing. I'll go back and try to get better pictures next week.
Photos of the plant would be helpful. Your pods are most cool. They remind me of the Guggenheim Museum in NYC.
Wow. Alfalfa's a pretty good guess. The leaves are really close (though I didn't get a good picture of them). I'll definitely try to get more shots.