Male - 23 Years Old
Since you mentioned Avett Brothers I am surprised no one has mentioned Paleface(guy did guest spots on Four Thieves and Emotionalism). Also check out Langhorne Slim, Old Crow Medicine Show, Holy Ghost Tent Revival, The Everybodyfields. The Avetts have also covered Jessica Lea Mayfield and she's definitely worth looking into. Dig into old country too, like Hank Williams senior, Roger Miller, etc.
Someone mentioned Damien Jurado and I second that. Elvis Perkins is great. The Gunshy is a gruff folk punk dude. Viking Moses is pretty neat and same goes for Paul Baribeau
There's always classics like Tom Waits, Leonard Cohen, Neil Young. Recent Springsteen albums are all pretty folky and there's always Nebraska.