For those of you not familiar with this fascinating area of numismatics, patterns are prototypes for coins that, for the most part, were never approved for circulation.
Most patterns are very rare, some unique, and others unknown outside of museums.
A good place to start learning about these pieces is our Beginner's Corner which includes a page on How to use this Website or the Photo Gallery which contains examples of many of the different pattern issues. The United States Mint produced well over a thousand different patterns, as well as many die trial and experimental pieces. Despite the great rarity of many of these individual items, the great variety makes the series surprisingly collectible. I'd estimate that there are approximately 200 collectors specializing in US patterns. Most of these collectors target specific areas.