What are they worth? No clue. Rare? They look like they could be. Safe? I would say they are as safe to use now as when they were made, assuming no major damage. They would be safe to use as they were designed. Probably for a lightweight car, without huge horsepower being driven as the conditions 80 years ago would have dictated. Are they safe under a hot rod running a Hemi being driven at today's speeds with quick take offs and harsh braking? Who can say for sure? They weren't built for that. So it depends how you intend to use them as to whether they are safe. I'd run them on that A.
I had some Hayes. Those had lock tabs to keep the "hub caps" from loosening on the fronts or overtightening themselves on rear driven wheels. Strange was that the left hand threaded ones were on the right side, and vice versa. If the locks were not working, the wheel drive pins can get worn out or egged. also check the spoke nipples under the tire tube flap when the tires are removed....they can rust very thin.