The ring is found in Sen's Fortress. There is a two story stairwell in the fortress with boulders running down it. If the player follows it they will reach a dead end hallway. Near the end of the hallway there is a room with a Mimic in it which players may stand in to stay out of the path of the rocks, and a deep pit at the end of the hallway. After three boulders pile up, the fourth will run over the filled in pit and destroy the wall, opening up a new room holding the ring. Be careful to move out of the way after grabbing the ring, as the boulders will continue to roll through the room and potentially kill the player.
The Covetous Gold Serpent Ring increases Item Discovery by 200. It does not stack with the Symbol of Avarice. Along with the Symbol of Avarice, the Covetous Gold Serpent Ring is one of the only items to increase item drop chance.
The ring is invaluable for hunting down upgrade materials for weapon and armor reinforcement, as well as rare items such as the Channeler's Trident.