We have all heard of the early American settler/colonial governor William Penn; he has a whole state named after him (his lesser-known cousin Del lent his name to a neighboring state when Penn angrily exclaimed "Gah, but my cousin be a twerp! Is Del aware that there is a whole unexplored expanse of forest only a day's walk from here? Let him go there, and leave us Quakers to our oats and motor oil!"). What is all but forgotten in our illustrious history is that while Mr. Penn's mother did not join him in the New World, her two youngest sisters Emily and Elizabeth did. Displaying the ingenuity and enterprising spirit that would come to characterize people of the United States, these two ladies quickly went into business making pastries, tarts, and sumptuous savoury turnovers for the hard-working Quakers of Pennsylvania and Delaware.
But life was rough in those early Colonial days, and while berries and other fruits were plentiful for their tasty tarts, there was not always enough beef, pork, mutton, or venison to put into their savoury turnovers. During a particularly rough year, Emily and Elizabeth began to substitute woodchuck and groundhog meat in their pot pies. When even those animals became scarce, they began to use rats captured from privies and middens.
When the good and pious people of the Colonies found out the awful truth, it caused a scandal which nearly resulted in the expulsion of the entire Penn family from the state that bore their name. In the years that followed, the whole thing was eventually hushed up and is now a mere historical footnote, known only to scholars and people who watch way too much Jeopardy.
Of course, what is forgotten to Americans is often remembered by the British, and 1879, composers W.S. Gilbert and Arthur Sullivan wrote and staged a light opera which gleefully lampooned the whole incident. Even if you haven't seen a production of this work, you must have heard of it.
They called it "The Pie-Rats of Penn's Aunts".