Star Candy

Star Candy is a rare item found in both Mario & Luigi: Bowser's Inside Story and Mario & Luigi: Dream Team, however in the latter, it is found in the form (and name) of Candies. It has a star-shaped appearance, and can be used by Mario, Luigi, or Bowser. This item restores 999 HP and SP and cures ailments, being the most powerful item in the game. It seems to have replaced the Golden Mushroom from Mario & Luigi: Superstar Saga.

The only exception is that an enemy (Dark Mechawful) can drop it so Mario and Luigi can have an infinite amount of Star Candies, while there are only 5 Golden Mushrooms in Superstar Saga (without cheats or glitches). It may also be given to the Bros. if the Special Attack Mighty Meteor is executed perfectly.

In Mario & Luigi: Dream Team, it's just referred to as Candies of varying potency. Candies heal 40% of Mario and Luigi's maximum HP and BP, Super Candies heal 60%, Ultra Candies heal 80% and Max Candies heal 100%.