An example of a Gold-Silver-Copper coinage system
The standard D&D gold/silver/copper system with its multiples of 10 comes from the Roman currency system of ~200BC-200AD. There were other Roman coins, but for the entirety of that time period, corresponding with the 'Classical' Roman 'golden age', the aureus, denarius, and as were issued in gold, silver, and bronze/copper respectively (the as went from bronze to copper during Augustus' reign around 23BC).
The ratios of those coins were 1 aureus = 25 denarius = 250 asses, so not quite the 1:10:100 ratio. However, the aureus was more than twice the weight of the denarius (7g to 3g) so if those two coins had been the same weight, then you would have the 1:10:100 ratio. The as was between 9-12g; its value decreased over time from 1/10 denarius to 1/16 denarius in 140BC, possibly as a result of financing the Punic wars with Carthage.
During Augustus's reign also another coin entered circulation. Now that there were 16 asses to a denarius, the sestertius was added at about 20-30g of brass and worth 4 asses or quarter of a denarius. This changed the ratio of aureus:denarius:sestertius:as to 1:25:100:400.
So the above is the coinage situation for 400 years of roman empire. What were these coins worth?
Relative value of coinage
In the late roman republic, a legionary was paid 112.5 denarius a year, or about 1/3 denarius a day (or two per week). Julius Caesar increased the pay to 225 denarius a year, or, or about 4 denarius a week. Tacitus says that the Roman army of the Rhine in the reign of Tiberius (~30AD) got 10 asses a day, and demanded a pay raise to a denarius a day (since at that time it was 16 asses to the denarius). By the reign of Domitian (~90AD) the pay was down to 1200 sesterces a year, which is 300 denarii a year, a little less than one a day.
For civilian pay, in the time of Diocletian (~300AD), a farm laborer was paid 400 asses a month (25 denarii a month) and a teacher paid 800 asses per month per student.
A sestercius in ancient Pompeii was probably the most used currency by common people. One could buy you two loaves of bread or a liter of wine (or less if it was good wine). 15 lbs of wheat ran about 7 sesterces, while the same of rye was only 3 sesterces. Slaves went for 2000-6000 sesterces.
The aureus was probably not used in by common people at all, nor was it used to pay taxes, which were often paid in kind (i.e. food) for use by the local military garrison. The aureus probably acted as a sort of reserve currency, like federal reserve notes today. It was minted in Rome, paid out to the provinces for civil servants salary, then paid back to Rome as taxes.
Non-precious metal currencies
In general, precious metal currencies drove out other forms of currency when they competed because precious metal currencies have the advantage of relatively constant supply and superior durability. From real world-evidence, you could conclude that more advanced economies that could perform large scale mining would eventually settle on precious metals. Therefore, other systems (like cowrie shells, or the like) would be used in less advanced economies and could be pegged to the precious metal system (10 shells to a copper, or something).
Alternatively, your world may have an item that is superior to precious metals. Mystic crystals could be available in limited quantities, with constant supply and superior durability, and have the advantage over precious metals that they have an intrinsic value to anyone doing magic. Therefore, mystic crystals would become the currency of the most advanced economy and gold/silver would be for lesser, peripheral economies.