I haven't time to read all above carefully, but I don't think this one was mentioned: "Pretty Sally," an old ballad often sung by Horton Barker, and a beauty. Sad, though.

Another which I used to sing for medical students- it always made them laugh: Leadbelly's, "Irene, Goodnight," which has the verse:

I love Irene, God knows I do,
Love 'er till the seas run dry-
But if Irene turn 'er back on me,
I'll take morphine and die!