The United States Mint was established in 1792 in accordance with the Coinage Act of 1792. Before
the US began minting its own coins, British, French, and Spanish coins circulated as standard currency
in the US colonies. The Coinage Act also established the dollar as the unit of money in the United
States, and created the decimal system for US currency. Originally, the Coinage Act stipulated that a
portrait of the president be on the obverse of all coins. In the final version of the Act, that was changed to allow an image emblematic of liberty, which is what is on America's first silver dollar, the Flowing Hair Silver Dollar.
The minting of the first silver dollar was a great symbolic step for the new nation, as it would now have its own circulating currency. However, the new silver dollar was delayed two years due to a provision in the Coinage Act that the top three officers of the US Mint (the Assayer, Chief Coiner, and Treasurer) had to post a $10,000 bond with the Secretary of the Treasury before minting any gold or silver coins. At that time, this was more than six times the annual salary of these positions. For this reason, only copper coins were minted until March of 1794, when the bond prices were lowered. That year, the mint struck 2,000 Flowing Hair Silver dollars from one set of dies.
Over 10 percent of these were rejected and destroyed as being too weakly struck, and minting of silver dollars stopped until May of 1795, when a new set of dies was finally created. The Flowing Hair dollars were minted for several months in 1795, but were replaced late in 1795 with a more refined Draped Bust dollar design.
Today, it is estimated that less than 200 of the 1794 Flowing Hair Silver Dollars remain in existence.
They are one of the most sought after coins for any US coin collector. When Flowing Hair silver dollars come up for auction, they can fetch great prices, as you can imagine. In August 2010, a 1794 Flowing Hair Silver Dollar set a record price for a US coin, selling for $1.2 Million dollars at auction at Bowers and Merena Auction Gallery in Boston, Massachusetts. Coins are rated by condition, and only 6 of the 1794 dollars are know to exist in mint state condition. This example is a Mint State (MS) 64, probably the best known example of one of the rarest coins in America.
I hope this gives you some insight into the story behind one of the rarest coins in America. Keep collecting and maybe you'll own one someday!