Pot

Pots are common items generated at world creation in random areas. When broken with any weapon or tool, they will either drop Coins and/or a random common item, or spawn a Coin Portal. The amount of items dropped is higher in Expert Mode. Furthermore, the amount of coins dropped increases with the number of different bosses defeated and the Wormhole Potions only drop in multiplayer. Pots cannot be picked up, never respawn, and cannot be crafted.

Coin Portals
On breaking a pot, there is a small chance that a Coin Portal spawns in place of the pot's normal drops. Coin Portals dispense between 5-15 Gold Coins one at a time before disappearing. It's speculated that coin portals are more frequent in the underworld but there isn't much solid evidence other than peoples' word