Collectible coins, particularly from the United States, include various types such as numismatic coins, commemorative coins, and bullion coins. A specific example is a roll of coins minted in Philadelphia in 2021, which may include modern coinage like dollar coins, quarters, or other denominations. Collectors often seek these items for their rarity, historical significance, or minting details, which can affect their market value. Coins from this era often reflect contemporary design themes and may be part of special series or events, increasing their appeal in the collectible market.