Dolly Parton’s music has often told truths, sometimes deeply personal, about American realities usually swept under the rug. You might not call it protest music, exactly — she doesn’t — but Parton continues her singular approach on Those Were the Days, the latest in her extraordinary run of albums for the bluegrass label Sugar Hill. She’s already tackled Woody Guthrie on her 9 to 5 album. Here she concentrates on an idiosyncratic set of ’60s and ’70s numbers. Not all of these are political songs, but the artist fits them into a musical and social context that’s bigger than movie-ready clichés; thank the unstoppably soulful side of her persona, if nothing else. Her cover of Cat Stevens’ “Where Do the Children Play” is filled with a soulful bitterness, while the idiosyncratic beauty of her “Me and Bobby McGee” makes you forget, momentarily, that the song was known far and wide before she took hold of it.