Annual lespedeza fills that niche here. Really comes on in July/Aug, and will reseed well, if you pull the cows off in Sept/Oct(when we'd be starting to stockpile fescue, anyway).
"Marion" performed exceptionally well in the severe drought of '98, and reseeded well, despite having to graze it(and anything else remotely green) into the dirt that year. Have had a hard time getting seed in recent years and have largely depended on the old Kobe and Kobe/Korean mix.
May not be as high-yielding as alfalfa, but grows on poorer ground, will tolerate a more acid soil pH, and doesn't require field prep - you can broadcast/'frost-seed' in Feb/Mar, let the cows trample it in, and still count on a good stand.
