I don't know about your players, mine are generally more interested in the VALUE of whatever coins they find, rather than what they look like!
That said, there is no better way of creating an air of realism about your campaign world than describing everyday items in loving detail. Never mind the headline stuff, the artefacts that everyone stops and looks at, it is descriptions of minor inconsequential stuff that really brings the place to life.
So, next time you come visit my city state of Barbridge, as well as sampling the fine ales brewed there you will get in your change (rattles her dice) a handful of hexagonal copper coins with a round central hole, showing a crab on one side and a patten of shamrocks & a crown on the other. Sounds a lot better than 'five copper pieces' doesn't it?
Now, she wonders, why does an inland township like Barbridge have a CRAB of all things on its coinage? Therein no doubt lies a tale... one that I may tell in the course of an adventure one day!
A fun little resource to add a wealth of flavour for a very low price!
[4 of 5 Stars!]