mint sets have certainly been around a long time, and many are very difficult to find and quite valuable. Uncirculated coin sets have been issued by the United States Mint since 1947 and have been offered almost every year since then - with a few exceptions. mint sets, which comprise collectible coins and the envelopes, internal packaging, and (sometimes) paperwork that accompany them. I’m a hobbyist who enjoys modern coins and ephemera (printed collectible memorabilia that was designed for short-term use) - so it makes sense that I enjoy collecting U.S. Uncirculated mint sets are among my favorite coin sets to collect. If you buy thru these links, we may earn a commission at no additional cost to you.