Gold coins are Sherwood Dungeon's form of currency. They can be used to buy weapons, shields, rings, and talismans from the merchants. Gold coins are not very hard to find and are littered all over the dungeons in groups of 2-40. Occasionally, a chest dropped by a monster may contain gold coins. All items except runestones, scrolls, diamonds, and gifts can be sold for a large amount of gold coins. Selling your items is the best way to earn gold coins in the game. If you are looking for a good way to gain gold coins, gather all the talismans and scroll weapons you can get your hands on; they sell at a very high price.
The game appears to have an upper maximum limit of 99,999 gold coins (verified for the Flash version of Sherwood Dungeon). Behavior in the game is such that when this limit is reached, players cannot sell items to the merchant. However, there appears to be a bug that still permits players to pick up coins from dropped treasure. If players exceed the 99,999 limit by picking up additional treasure, they can sell items to the merchant. But the game will reset their treasure amount back to 99,999 upon exiting and re-entering the game.