For those who don't know, an airborne object crashed on a ranch near Roswell, New Mexico, on July 7, 1947. Although a US military surveillance balloon is said to have crashed, a second explanation is that the object was a spacecraft containing extraterrestrial, alien lifeforms which were ultimately transferred to the super-secret military Area 51 in Nevada. A Google search on UFO, or unidentified flying object, retrieves a plethora of information on the subject, including some information that is, presumably, highly reputable.
In commemoration of these and similar events, you can own a nice ALIEN QUARTER as shown in the picture. The form depicted is the most popular interpretation of what the alien lifeforms look like. A good place to get an alien quarter is LookTokens.com. Prices range from $5 to $20 per coin. The web site says they are made from actual US quarters, so they contain no precious metal.