Historical and collectible Gold legal tender coins.
These are coins that were at one time used as money. However the value of gold they contain now far exceeds the face values. As collectibles they also have rarity issues as well, and for many high grade coins the market value is many multiples of the precious metals they contain.
The US stopped using gold in money in 1933, and stopped redeeming dollars for gold in 1971. No countries use gold as circulating currency at this time.
Prices will fluctuate with the spot price of gold.