Alan Lomax, The Folksongs of North America, 1960, no. 83, pp. 165-166, with brief musical score.
The same verses as posted by 'witz, 25 May 11 but with the addition of the muskrat verse:

Muskrat, O muskrat, What makes you smell so bad,
I've been in the bottom all my life
'Till I'm mortified in my head, head, etc.

"From singing of Aunt Molly Jackson, Clay County, KY, collected and arranged by Alan Lomax."
Melodies and guitar chords in this book transcribed by Peggy Seegar.