The Antiquity of the Novelty Song

An odd thing I discovered while searching for details of a quite different nursery song for someone.
Nursery Antiquities, from Popular Rhymes and Nursery Tales by James Orchard Halliwell

"The following has been traced to the time of Henry VI., a singular doggerel, the joke of which consists in saying it so quickly that it cannot be told whether it is English or gibberish:

"In fir tar is,
In oak none is,
In mud eel is,
In clay none is,
Goat eat ivy,
Mare eat oats."

(Assuming you all know the song "Mares eat oats"?)