Gold Medal (Yoshi Topsy-Turvy)
From the Super Mario Wiki
A Gold Medal (also known as a Gold Happiness Medal) is a collectible in Yoshi Topsy-Turvy. A Gold Medal is earned if Yoshi earns a higher score than the one required by the Spirits. For example, collecting a much higher number of Coins than the target set by the Spirit of Greed will earn Yoshi a Gold Medal. Additionally, collecting a Gold Medal gives the player better odds at winning the Bonus Chance!.
Winning a Gold Medal in all levels will unlock the Bonus Game Shuffle Mode EX, which is accessible from the game's main menu.