Coins, especially collectible ones, include a wide variety of special types such as patterns, trial coins, and commemoratives. Patterns are experimental designs submitted for approval before minting, often featuring unique designs that never go into production. Trial coins are struck to test die and design before mass production, particularly noted in the 1800s for their rarity and historical significance. In the context of United States currency, the one-dollar coin has seen various iterations, with enthusiasts often focusing on limited minting years or unique characteristics. Collectible coins are subject to market dynamics based on rarity, demand, and historical context.