In the realm of collectible coins, the United States has a rich history that includes unique items such as patterns and trial coins. The 1822 fifty-cent piece is a notable example, as it represents an early attempt to establish a standard design for U.S. currency. Patterns are experimental coins struck to test designs, while trial coins serve as proofs of concept for various minting techniques. These types of coins are highly valued among collectors due to their rarity and historical significance.