A Flower Box is (obviously) a box of Flowers found in Super Mario RPG: Legend of the Seven Stars. When used, this item increases Mario's Flower Points by a whopping five FP! As such, Flower Boxes are very rare and usually found after defeating an extremely tough boss. In addition to increasing Mario's FP by five points, a Flower Box recovers all of Mario's FP.
Note: A Flower Box must be used on the item screen before Mario's FP is increased, unlike regular Flowers which instantly increase Mario's FP when picked up.