Pea was the Princess of Duloc.
Shrek the Musical
In the "Ballad of Farquaad", it was revealed that she was the princess of Duloc. She married Grumpy for love, and in turn was disinherited from her title. After marring Grumpy, she had a child, which she named Farquaad. One night, she had a hard time sleeping on the couple's lumpy mattress, so Grumpy stacked 25 mattresses on top of one another to ease her sleeping. However, due to the great height, Pea fell from the top of the mattresses to her death.