Collectible coins from the United States, particularly those from specific years such as 1999, can include various denominations and series. One notable type is the statehood quarters, which were released as part of a program to honor each state. Rolls, typically containing 40 coins, can be sought after by collectors, especially if they feature rare mint marks or errors. Dollar coins from this era, including the Sacagawea dollar, may also be popular among collectors due to their unique designs and limited mintages. Collectibility can be influenced by factors such as condition, provenance, and market demand.