Almost half a century after putting out an album of Appalachian folksongs, Ellen Kossoy again encountered the music of her youth in a most unlikely way. Sitting in a movie theater with scenes from O Brother, Where Art Thou? flickering across the screen, she hadn't expected to hear the voices of anyone she knew personally. Imagine her surprise when she heard her own voice, along with that of her twin sister, Irene Kossoy, come floating through the air. "I'll Fly Away," one of the songs the Kossoy Sisters had recorded during the 1950s for their Tradition Records' album Bowling G...