Shell Earrings
The Shell Earrings were stolen from the Toad Waitress on the Excess Express by Doopliss (who was disguised as Zip Toad at the time) during Chapter 6 of Paper Mario: The Thousand-Year Door. The Shell Earrings were meant to be a part of the Shadow Sirens' plans to create an explosive form of Nitro Honey Syrup; in order to do so, they needed Nitro Honey Syrup plans from the Businessman's briefcase, a source of gold (Toodles's Gold Ring was what they chose), and a source of seashell calcium, the Shell Earrings themselves. However, Mario put an end to their plans, retrieving the lost items. If Mario gives the Shell Earrings back to the Toad after doing so, she will give him a Star Piece.
According to in-game descriptions and the Toad Waitress herself, the Shell Earrings were given to her by her ex-boyfriend, who apparently talked to her via telephone shortly after Mario returned her earrings. Mario may have actually met this ex-boyfriend, as talking to a certain unnamed Squeek (who often tells Mario of his many love relationships) after beating Chapter 6 will reveal that he was once in love with the Toad Waitress and apparently did give her earrings during this relationship; he also wonders if the waitress still cherished them as he spoke to Mario.
