1928 Graham-Paige, last year for wood spokes has 4 bolts on outer edge. I did find a picture of one on the web with that exact design. I don't know how to pull pictures from the web to post, or I would have.
I figured someone would know what it was for. A buddy came across it and was curious. Has a chance to buy all 4.
Thanks, but I can't take credit for it, I just did an image search on Google from Studeynut's and Skirtless33's posts saying what it was.