“Lucky pennies” are still common charms and souvenirs (a friend brought me this one in a tiny ‘witch bottle’ from a visit to Salem many years ago) kept for luck, prosperity and gambling success. Some coin amulets are special “lucky coin” medallions, but usually an ordinary coin is used, either worn as a pendant or bracelet, or put in a “mojo bag” with other magical ingredients. Besides being used for luck, coins can also be used for personal magical protection against malign witchcraft or the Evil Eye. Silver coins are especially used for this purpose; when a silver coin charm turns black, it is supposed to have successfully turned away something sent to harm you.
Although any coin can be used as an amulet or charm, the variety of images stamped on them means that some are believed to possess more magical power than others, and some are especially suited for particular uses. In the US, two coins traditionally used for gambling luck and protection were the Indian Head penny and the Silver Mercury dime. The dime (shown above) was doubly effective because it was solid silver - a protective metal - and because it showed a figure of Mercury, the Roman god of the crossroads, gambling and communication. (Actually the coin was meant to depict “winged Liberty”, but nobody has ever seen it as that.) Additionally, coins with significant dates - leap years, your own birth year, etc - are especially potent.
These two coins, of course, haven’t been minted for almost a century (though they’re easily available from coin dealers for only a few dollars each) but there are lots of modern coins whose images make them very suitable for magic use. The US has two one-dollar coins still in circulation, both depicting strong women whose image would be useful to invoke in magic charms or spells: Susan B. Anthony for political action, protection of civil rights or perhaps sobriety (she was a leader of the temperance movement) and Sacagawea for travel, finding your way, or even clarity of understanding (although she's known as Lewis and Clark's guide, she mostly acted as a translator). As well, the dollar shows Sacagawea holding her newborn son, giving it a correspondence to motherhood, family and childbirth. In Canada, the mint has just issued two quarters commemorating the War of 1812 that will be very good for protective magic; one shows General Isaac Brock and the other the Shawnee chief Tecumseh, who together defended Canada from the invading US forces. The red enameled maple leaf on some of the quarters could make them even stronger magically, as red is a colour traditionally used for magic charms.
So what can you do with these coins, magically speaking? Well, the simplest and most traditional thing is simply to keep them on your person, either made into a piece of jewelry or just kept in a pocket or purse. A coin can become a protective amulet simply by your recognizing it as such, but most people will want to do some ritual to “magic it.” This can be as simple or elaborate as you prefer, but will usually include cleansing to remove any existing energies from the coin, consecrating or blessing it, such as with holy water, incense, condition oil or moonlight, and charging it with your intent. The longer you wear the coin or keep it on your person the more it will become part of your magical personality and respond to your needs.
But coins are also often incorporated into mojo bags, talismans or other magical artifacts. In traditional American witchcraft, silver Mercury dimes were often included in witch bottles, mojo hands or other protective creations, along with herbs, roots, stones, spell papers, animal parts or other ingredients. If the charm being made is very small, sometimes only a sliver or a few filings from the coin are included, but it is still enough. Usually the coin is just sewn into a packet with the other materials, but for protective amulets I like to keep the coin visible, as on this little house protection charm I made. Because coins are shiny and round, they have long been used to deflect the Evil Eye and other malign influences, so by featuring the coin on the outside, you get extra magical value from it. Coins can be drilled and sewn on like sequins, but one excellent way to attach a coin to a fabric pouch is to sew it on like a shisha mirror. Here is a simple tutorial on this, from Joyful Abode. I’ve used a tiny Swiss coin with an image of an armed woman carrying a shield, and filled the packet with three protective herbs: basil, rosemary and elderberries. This would be a good charm to hang over your door, with the coin facing out to anyone approaching your home.