For what it's worth, I found this quote in a Project Gutenberg eBook: Four Boy Hunters or, The Outing of the Gun Club by Captain Ralph Bonehill, 1906:

...then he began to sing softly.
"Ham in the pan! Ham in the pan! Ham's the best of meat!"
"Ham in the pan! Ham in the pan! Ham is good and sweet!"
"You stop that!" roared Ham Spink, and then, as a dozen boys on the dock took up the darky song....