Collectible coins include various types of currency that are sought after by numismatists for their rarity, historical significance, or unique characteristics. The United States quarters, especially those minted in 1990 at the Denver mint, can be part of sets or rolls that feature specific designs or themes. A 25c roll of quarters typically contains 40 coins, totaling $10, and these may include both circulated and uncirculated specimens, impacting their collectibility. Collectors often examine factors such as mint marks, condition, and production errors when evaluating the value of these coins.