Golden Treasure Chest
From the Super Mario Wiki
The Golden Treasure Chest is an item in Super Mario RPG: Legend of the Seven Stars. The Golden Treasure Chest is a Treasure Chest created by a Magikoopa that serves Bowser. This Chest is like most others except for the fact that it has a gold color and has an infinite supply of coins in it for Mario to use. This Chest can be found near the back of Bowser's Keep. The box is created by Magikoopa after Mario and party defeat the brainwashed version of him in a fight in the keep.
The Golden Treasure Chest reappears in Super Mario Galaxy in the Bigmouth Galaxy. Instead of containing coins, the chest contains Captain Toad, who will give Mario a Power Star. However, the only way to open this chest is to throw a Gold Shell at it to break the lock.