Buckwheat is a good cover crop but not a legume so some kind of pea cut before it produces is a good choice. We have problems with common vetch and I don’t like it because it just goes nuts.
Rye is good in cool weather and I should have planted it last fall. It truly is green manure and smells like it when you turn it under as well.
Sometimes I think we’d be better off with raised beds but I like stuff in the ground just because. I have gotten over my shock of concrete blocks and may try that. So many projects and so little time and I am running short of it like we all will.
I’ve found peas and tillage radishes to be a good combination in the summer. The radishes grow to the size of my arm, which really loosens up my heavy clay soil. The peas love to climb thistles and smother them. And if things suddenly go south, both can be used as a food crop instead.
I’ve started planting winter rye in the fall. Hoping eventually I’ll get the weeds under control.