As of 2015, America’s coinage is limited to just six denominations: 1c, 5c, 10c, 25c, 50c and $1. Of those six units, most people encounter just the first four; the half dollar and dollar circulate somewhat infrequently. With that in mind, it might come as a surprise to the average American that our country has produced coins in seventeen (!) different denominations. Granted some of these were short-lived and were phased out over a century ago, but they continue to be fascinating keepsakes and treasured collectibles. Below is an overview of the more unusual denominations and how they came to be:

Half Cents: Nowadays, it’s hard to think of buying anything worth less than a quarter, let alone less than one cent! However, in the late 18th and early 19th centuries, the Philadelphia Mint struck a significant quantity of copper half cents. The coins were first released in 1793, but by the 1850s inflation had rendered them unnecessary. The last coins were struck in 1857.

Two Cent Pieces: The one cent coin was the “workhorse” of American commerce in the mid-19th century. Many products that cost 50c to $1 today were just a penny in the 1800s. Given how many “pennies” were needed for day-to-day trade, the US Mint decided to also release a two cent coin. Unfortunately, it never caught on and the denomination lasted just a decade.

Three Cent Pieces: This denomination was issued as a tiny silver coin from 1851-1873 and as a slightly larger nickel coin from 1865-1889. It was first conceived as a way of paying for postage stamps (which cost 3c at the time) but it received only a lukewarm reception from the public. The silver coin, in particular, was criticized for being much too small.

Twenty Cent Pieces: Simply put, this coin existed to satisfy mining interests, not the general public. After silver was discovered in Nevada, some politicians put pressure on the US Mint to strike more silver coins. The twenty cent piece was an ill-conceived means of converting more silver into coinage. The coin was constantly confused with the quarter. It was produced for circulation in 1875 and 1876, then struck in proof format for collectors in 1877 and 1878.

Three Dollar Gold Pieces: This denomination was the “big brother” to the three cent coin; it was designed to facilitate paying for sheets of 3c postage stamps. Furthermore, thanks to the California Gold Rush, the US Mint was flush with gold in the early 1850s—it was eager to release a new gold coin. Like its smaller sibling, the coin saw limited popularity and was unceremoniously discontinued in 1889.

Four Dollar Stellas: This is the most valuable of the odd denominations, with specimens trading for anywhere between $30,000 and $2.5 million. The $4 gold Stella, named after the star on its reverse, was produced for international trade. Although the coin’s weight and size was unusual for an American coin, it was similar in weight to many coins produced abroad. The coin didn’t make it past the prototype phase and it was never officially released for circulation.