Martha is probably best known for attempting to sell Martin's extremely valuable Star Wars merchandise to Comic Book Guy for extremely cheap. She was warned by Bart and Milhouse before she sold them and she decided to not to sell it. In Wild Barts Can't Be Broken, it's revealed by her son that she "shoplifts all the time, mostly just for stuff she doesn't even need."
She was also responsible for all of the guests at Martin's birthday party (with the exception of Seymour Skinner, Edna Krabappel and Bart and Lisa Simpson) getting food poisoning because she had served diseased oysters instead of cake.
- Seymour and Edna didn't get sick because they were in Martin's pink playhouse and didn't receive any oysters.
- Bart didn't get sick because he fed his oysters to the Prince family pet cat.
- Lisa, being a vegetarian, didn't eat any of the oysters--she merely pretended to have gotten food poisoning from them so she could have an excuse to leave the party without looking rude.
- It's possible that Mrs. Prince may have kleptomania, due to Martin's comment about her shoplifting habits.
Note: Many of her appearances are brief background roles. The episode in which she has an actual role is in bold.