Image from Library of Congress “Foodways” collection. Michael Hurley, the godfather of freak folk, died in April. Now we have his last, posthumous album, which was released in September and offers a final occasion to look back at his contributions, always arriving slightly aslant, to folk music history. An outsider artist but no museum-room oddity, Hurley was an authentic American avant-gardist, like Emily Dickinson or Ornette Coleman. When I saw him at the Brooklyn Folk Festival last November he walked onstage to a hero’s welcome. The show was in a great dark church and those of us who didn’t arrive in time to fill the pews found space on the floor, sitting at his feet. Skeletal, serious, with a handkerchief around his neck and a pipefitter hat shading his eyes, Hurley sang out in a tremulous voice. A few times in the set he paused for a moment—Had he forgotten the words? I wondered—but only to summon some invisible inner current. He was funny, he was grim.…