Collectible coins refer to coins that are sought after for their historical significance, rarity, condition, and potential for appreciation in value. In the United States, notable collectible coins include patterns, which are experimental coins struck to test designs or compositions before official production. One significant example is the 1823 pattern coin, which showcases unique designs that often differ from standard circulating currency, making them highly desirable among collectors and numismatists. These coins are typically produced in small quantities, contributing to their scarcity and value in the marketplace.