If you want Bluegrass covers, try Hayseed Dixie. They started out as an AC/DC cover band, but then diversified out to other covers and original songs.
Plus, I heard an interview with them on the radio and they slagged off Coldplay.
"They that band that has that song 'bout how everythin's yellow? I never got that. Not enough sex, booze and dealin' wid the devil for my tastes..."