From the Super Mario Wiki
Super Mario RPG: Legend of the Seven Stars
In Super Mario RPG: Legend of the Seven Stars, Ultra Mushrooms are known as Max Mushrooms, have yellow caps, and completely refill one party member's HP when used.
Paper Mario series
Ultra Shrooms are never sold by shops and are instead found randomly throughout the Mushroom Kingdom in the first Paper Mario. Occasionally, an Amazy Dayzee will drop an Ultra Shroom when defeated in battle.
In Paper Mario: The Thousand-Year Door, very few places sell Ultra Shrooms; however, they may be purchased for 200 Coins each at the Deepdown Depot, the shop in Rogueport Sewers, and they can also be found in the Pianta Parlor for 67 Pianta Tokens. Charlieton occasionally sells Ultra Shrooms for 120 coins.
In Super Paper Mario, Ultra Shrooms are found hidden within ? Blocks. Due to their high HP recovery, they are generally found before boss battles during the later chapters of the game. They heal 50 HP on contact with the player, and their carry-on equivalent is the Ultra Shroom Shake.
Mario & Luigi series
In the Mario & Luigi series, Ultra Mushrooms refill 120 HP in Mario & Luigi: Superstar Saga and Mario & Luigi: Bowser's Inside Story, 80 HP in Mario & Luigi: Partners in Time and Mario & Luigi: Superstar Saga + Bowser's Minions, and 100 HP in Mario & Luigi: Dream Team and Mario & Luigi: Paper Jam.
Names in other languages