There is no silver content in the 1964 nickel. The U.S. Mint stopped putting silver in 5-cent coins back in 1866 and began using copper and nickel instead.
The 5-cent coin has not always been called a "nickel." It was first named a "half-disme" (pronounced as "dime") and was much smaller than the modern nickel. However, half-dismes were still produced until 1873.
In 1938, Thomas Jefferson became the president featured on the obverse (heads) side of the nickel, and Monticello, Jefferson's Virginia home, became the focus of the reverse (tails) side of the nickel. Jefferson and his home remained on the nickel until 2004.