Silver coins struck by the US Mint were standardized with the production of what became known as the Morgan Silver Dollar in 1878. These coins were the result of an Act of Congress that required the government to buy silver at prices above market price and issue coinage from that silver.
Minted at a time of reduced silver value, these coins were nevertheless favored as symbols of the old west (so many having been minted at the Carson City Mint as a result of discovery of the Comstock Lode). Today, as the price of silver has appreciated, these coins are a great and relatively inexpensive way to begin precious metal investment. They have always made great gifts. From 1878 to 1904, and again in 1921, the US Mint struck Morgan dollars; from 1921 through 1928, and again in 1934 and 1935, the US Mint struck Peace dollars. Both featured a bust of Liberty. Each contains about .773 ounces of silver.