Page 22 of 50. John F. Kennedy half dollar.

Mine!
One of the most popular coins ever has been the JFK half dollar. It has a unique history as well.

Most know JFK was assassinated on November 22, 1963 in Dallas, TX. There has been an ongoing controversy about just who killed him. I'll stay out of that here for now, except to say, I do not believe the government's story. Nuff said for here.

The Kennedy half-dollar was rushed into production. Those silver coins vanished from circulation upon their release in March 1964 due to collectors, hoarders, and those simply interested in a memento of the late president. Although the Mint greatly increased production, the denomination was seldom seen in circulation. Continued rises in the price of silver increased the hoarding—in fact, many early Kennedy half dollars have been melted for their silver value. Starting with 1965-dated pieces, the percentage of fine silver was reduced from 90% to 40% (silver clad), but even with this change the coin still saw very little circulation.

In 1971, silver was eliminated entirely from the coins.

The late president's widow, Jackie, preferred that he be depicted on the half dollar. Mrs. Kennedy viewed the designs favorably, but suggested that the hair be altered slightly. They did whatever she asked.
Jackie Kennedy
When the Treasury Department made the coins available to the public beginning on March 24, 1964, a line a block long formed at the department's windows in Washington to purchase the 70,000 coins initially allocated for public sale. Even though the department limited sales to 40 per customer, by the end of the day the coins were gone, but the line had not shortened! Eventually, almost 430 million half dollars dated 1964 were struck, a sum greater than the total struck for circulation in the sixteen years of the Franklin half dollar series.

Where the hundreds of millions of them went remains somewhat of a mystery today.
  
Excerpted and slightly altered from Wikipedia: Wiki

Remember that year - 1964. After that date just forget about "silver" coins! The few exceptions aren't worth bothering with. When the dollar crashes you wont want to be educating people into believing your 2004 Proof DCAM Kennedy is 90% silver! It is - but do you want to go through all that?

NEVER TAKE MY INVESTMENT ADVICE! 
Consult the professionals