Sorry if this has been mentioned, but I didn't read the whole thread.
Mike Cross was mentioned in the first post. He also did a song called Elma Turl, based on an old joke. I heard Buffy Sainte-Marie sing an entirely different song based on the same joke.

ELMA TURL
(Mike Cross)

Elma Turl is a beautiful girl, and I'd love to have her for my wife.
She's just the kind of woman who could make me happy for the rest of my life.
My daddy said, "Son, there's something you don't know, and it's something I think you oughter.
Elma Turl is a beautiful girl, but son, she's my daughter."

Alice Green is a beautiful thing, and I'd love to have her for my wife.
She's just the kind of woman who could make me happy for the rest of my life.
My daddy said, "Son, there's something you don't know, and it's something I think you oughter.
Alice Green is a beautiful thing, but son, she's my daughter."

Well, I've been all around the whole durn county, like a buck huntin' for a doe,
But it seems every girl I'd like to marry is a wild oat Daddy sowed.
So I went to my mama with my head hung down, and she asked me what the matter could be,
I told her my problem and she took my hand and said, "Son, now listen to me.

"You see, your daddy was such a good-lookin' young man, and like an eager young stallion horse,
His blood ran hot, so you can't blame him for lettin' Mother Nature take her course,
But you got no reason to be upset. Don't you worry; don't fret; don't bother.
You see, your daddy ain't your daddy. He only thinks he is, so you can marry whomever you wanter."