Most silver coins, rounds, and bars have some history tied to them. It could be the design stamped on it. It could be the location or time period in which it was manufactured. Or in some cases, like the round I'll show you today, the history is the metal from which the rounds were made.
In the 1960s, the US government had huge stockpiles of silver. Then they stopped using silver in the coinage in 1965. They eventually decided to dump a bunch of silver onto the open market which drove the prices down.
Some of this "Strategic Silver" was used specifically to mint rounds that advertised the origin of the contents.
In this picture you can see it says "Minted from US Strategic Stockpile Silver."
It may not be the most groundbreaking thing, but I still appreciate the significance of silver that was once used to help financially back our country. The USA is no longer on the gold standard, and it is debatable as to how much gold the government actually has in precious metals reserves, but at one time they had a lot... and this was a part of that.