Back on Halloween 2014, Tony Joe White sat in with the Foo Fighters to play his signature song “Polk Salad Annie” on the stage of the Ryman Auditorium, the onetime home of the Grand Ole Opry. Ironically, White — the country-funk singer and guitarist known as the “Swamp Fox” — had yet to appear on the Opry. That honor would come about four years later when he made his Opry debut on the same day he released Bad Mouthin’, his album of country blues. Bad Mouthin’ would be White’s final album, and