From the Super Mario Wiki
Super Princess Peach
Large Coins first appear in Super Princess Peach, each worth five coins. Upon buying a Courage Soda, Princess Peach and Perry can knock Large Coins out of enemies as well as finding them throughout levels. In this installment, Large Coins bear a resemblance to Blue Coins from Super Mario 64.
Super Mario Galaxy 2
A Large Coin also appears in Super Mario Galaxy 2. It was seen in Supermassive Galaxy. Mario had to Wall Jump on the Large Coin in order to progress through the galaxy. However the gigantic coin would spin around at times making it harder for the player to wall jump on it and progress through the level. The coin cannot be collected though.