Susan B. Anthony was born in 1820 and would eventually change the course of history for American Women. Susan is responsible for women's suffrage (the right to vote). The Susan B Anthony coins however were not so successful. They were only issued from 1979-1981 (3 years), and then again in 1999. The coins were issued at the Philadelphia and Denver, and San Francisco mints. The FG found under the bust on the obverse are the initials for the engraver Frank Gasparro.
As a rule of thumb the wide rim SBA's are worth more than those with a narrow/slim rim. In addition be sure to look out for clear vs non clear S mint marks. A clear mark is worth more.
The Susan B Anthony dollars are not made of silver. They are 75% copper, 25% nickel, clad to pure copper core.