"A rare clover. It's prized by leprechauns for protection and good fortune."
The Four-leaf Clover is an item which will extend the ghost timer by 2 minutes upon pickup. But if the ghost has already appeared, then the clover will no longer help. It is a guaranteed drop from Leprechauns but can also be found in specific locations (e.g. the Moon Challenge, Vlad's Castle, etc.).
Will spawn a half-rainbow sprite somewhere in a level occasionally. If you bomb right underneath said sprite, a Pot of Gold will spawn and whipping it will sequentially spawn coins until breaking up to a value of $6000-10000.