This may seem like a normal gravestone, but look carefully at the very bottom of the photograph.
A little digging revealed that an age ("62 y'rs & 10 mo.") was carved on the stone upside down. This wasn't Fanny's age at death, but it was the age at death of her husband's first wife.
Here's my theory: the first wife dies in 1837 and a stone is erected. The husband remarries, dies in 1849 and a new stone is made for the first wife to complement his own. The second wife dies in 1871, and her evil or indigent step-children recycle their mother's old stone to mark her grave.
Only chilly fingers and fear of prosecution prevented me from pulling this stone completely out of the ground to prove my theory.