YONDER MOUNTAIN STRING BAND8:30 p.m., Revolution. $20.
Talk about pickin' and grinnin'. These progressive, country- bluegrass jammers
seem to be simply buddies who like to make music together. The band's history stretches back to when banjoist Dave Johnston and mandolinist Jeff Austin were still in college. Having met in Urbana, Ill., Johnston asked Austin to join and sing in his band the Bluegrassholes. Austin, who played no instrument, revealed to Johnston that he owned a mandolin, which prompted Johnston to tell him to come on down and “play anything, just play fast and loud.” Austin is also known to break into freeform scats during songs. With nine albums behind them, five of which are volumes of live recordings, this all-ages, taper-friendly show could stretch for a while.