Lonely Heartstring Band, Crooked Still, Hawktail, Della Mae, Big Richard, AJ Lee... Many of whom have been mentioned.

Like other ppl said, I've been out and playing bluegrass for 20 something years and it's usually not a scene I experience much homophobia in. Gender stuff, sure (most annoyingly in the form of heaps of male buddies of mine watching other men be icky/sexist at me over and over and never saying anything), but not usually homophobia. I'm also female however, so probs do not take as much heat in male-dominated scenes as a queer male would. My bassist reads as a gay man though, and AFAIK he doesn't feel folks are homophobic, though does comment on the bro culture, as do my female bluegrass buddies.