Coffee is a type of drink found in the real world and the Mushroom Planet. It has made a few minor apperances in Mario games. In Super Smash Bros. Melee, Coffee appears a long withall the other Food items. If a character drinks coffee in the game, the character will heal two HP.
In Mario & Luigi: Superstar Saga, E. Gadd runs a cafe called the Starbeans Cafe. Mario and Luigi can make coffee here, however they need Beans to make coffee. The borthers can drink the coffee and depending on which type of beans they used to make the coffee, different stats will go up.
In Paper Mario: The Thousand-Year Door, there is a food called the Mushroom Full Course served in the Excess Express. This food has a type of coffee called "Mushroom Coffee". In Super Princess Peach there is an item called "Tough Coffee" that heals Princess Peach half a heart. In Super Paper Mario in the Overthere, Carson sells coffee.