Of course! They're made of gold! Gold can be melted down and traded for any currency in the world; it's the most commonly recognized currency in the world! There are lots of shops that will melt them for you.
Unless they happen to be particularly old the value is likely to be coin's weight in gold. If they are collectible the value will be in the specific coin.
It depends upon how old the coins are. First of all, as gold coins, they are certainly worth their wait in gold. Suggest speaking to an antique dealer.