Cloverleaf

Sold by Nazramu, a djinn you "pulled" into your world using Spectacles of Spectacle during Zaviak's Vision Quest.

In-game description
"The halfling Tip Eldermaple was noted in his town for never losing at cards. The halfling attributed his good fortune to the blessings of Tyche and lived a long, quiet, and very prosperous life. When Tip finally died at the age of one hundred and three, he left his favorite belt to his son, who discovered that the belt buckle had caught a four-leaf clover in the clasp. Whether Tip had placed the clover there himself, or whether it had simply been stuck there after a tumble down a hill in his youth, no one will ever know. What is known is that Tip’s fortune passed down to his son, until the belt was stolen from him by an ogre while he was traveling along the Sword Coast."