Which Mario Kart game first featured the Golden Mushroom item?

Mario Kart: Double Dash!! was the first Mario Kart game to feature the Golden Mushroom item.

The Golden Mushroom gives a racer repeated boosts for a limited period, allowing the player to press the item button multiple times instead of receiving one single speed burst. In Double Dash!!, it was especially useful on long straights or when recovering from a poor position.

The item is easy to confuse with the ordinary Mushroom, which had already appeared in earlier Mario Kart games. Mario Kart 64 featured a regular Mushroom, but not the Golden Mushroom as a distinct item. Later games reused the Golden Mushroom, sometimes making it available through item boxes and sometimes assigning it to specific racers or modes.

Double Dash!! was released for the Nintendo GameCube in 2003. Its defining feature was cooperative two-character racing: one character drove while the other handled items, with players able to switch roles during a race.