You could grow mesquite for the pods. I think it’s native to your area.
Northern-adapted pigeon pea as a short-lived perennial.
Sword bean, jack bean.
I heard about mesquite through the carbon farming solution. They have quite a few perennial crops in there, including protein crops.
If you can overwinter them
Vigna vexillata (zombi pea)
Runner beans
Chia
I’ve eaten plenty of redbud pods (another legume family tree) but I’m not really sure how much protein they have. They are much more pod than seed.
Hopniss is like a higher protein potato that also makes edible bean seeds. I’m surprised it’s not a bigger deal in permaculture circles (or maybe it is and I just don’t know).
Given how edible the mallows are, I’d be surprised if there isn’t a perennial crop grown for its protein-rich seeds. I’ve definitely eaten Rose of Sharon pods/seeds, though the pods are a little tough and a little small.
Basil has high protein content in the seeds, though like chia will have to overwinter and might be more fiddly than desired.
Finally if you want to get really bold and crazy and make your neighbors hate you, perennial ragweed. Seems ragweed may have been the crop maize replaced. Doesn’t taste great but supposedly very nutritious and protein rich. Come on, neighbors. Make a ragweed tincture and see your allergies improve like never before
More seriously, I found the carbon farming solution to be a good resource and I think Lowell grows a number of perennial legumes.