Thanks for the references. Looks like it may be native American after all, though showing the influence of British balladry. I've noticed that Bill Jackson, the singer on the Voices From the Dust Bowl version, sings many of his ballads to modal melodies that often sound Scottish or Irish. But I still think there may a British antecedent from which the original (anonymous?) composer borrowed. Interesting that the ballad seems to have been confined to Missouri and Arkansas.