Collectible coins include a variety of types such as proof coins, commemorative coins, and minted sets. The 2016 Proof Sets from the San Francisco Mint typically feature coins struck with high-quality finishes and are often sought after by collectors for their detail and luster. The 25-cent denomination, commonly known as the quarter, may be included in these sets, showcasing designs that reflect American history and culture. Collectors value these items for their artistic merit and potential for appreciation in value over time.