My mother, an otherwise dignified professor of voice, used to sing "Go On, Mule" accompanying herself on ukulele. She said she learned the song as a child in the 20s, but she taught at the Georgia State Women's College in the 30s and early 40s, so may have heard it there, too. Alas, I never recorded her version, and all I remember a verse and chorus.

Oh, Rastus Aches and Georgia Pains
Were married down in Plains
And now they say the Georgia woods
Are full of Aches and Pains

Go on, mule
Don't you roll dem eyes
You can change a fool
But the doggone mule
He's a mule until he dies

I'd like to learn the full lyric myself.