A different approach to take is one of symbolism.
In Raymond Feist's Empire of Tsunami (The Empire Trilogy) metals are incredibly rare. As such only the richest lords and ladies can afford metal weapons. As such the value of any metallic coin would be worth far more than any normal citizen would ever earn in a lifetime.
As such a currency of counters is used (wood I believe). Much like paper money today (after all the paper a £20 note is printed on is worth far less than the value of the note). For this system to work the token must have the same value for each person, there must also be a level of trust and uniformity. In other words it must be organised my a higher power - a national bank or the crown for example.
Originally in western civilization this token system was developed with the paper represented real money in the bank. Indeed in the UK many of our notes still have printed "“I promise to pay the bearer on demand the sum of...".
Given this it's possible that a note/token could be paid out of a common material and used to represent one (or indeed 1/100, 1/1000 or 1/1000000) unit of valuable material (gold, silver, gems) stored by a trusted authority elsewhere.
The upshot of this from a world building perspective is you can actually use all sorts of weird and wacky currencies if they're set up and regulated by the ruling classes. If they pay their workers in beans (remember the Star Trek Voyager Ferengi episode with ears!?) because those beans will be regulated and authorised. People will trust them and will be willing to store their wealth in beans.
An aside but fascinating example. If you've ever played the online game Guild Wars there's a fantastic economy which has built up around ectoplasm. A character can hold a maximum of 99 platinum (which equates to 99,000 gold coins). As a result the elite players frequently hit upper limits on how much they could store. However you had far more space to store equipment. There is a substance dropped by some baddies (very rarely) in the elite levels which is used to craft the prestige armours. As a result many of these elite players wanted ectoplasm, and they could store far more of it than they could money. As a result a huge market opened up for ectoplasm with prices fluctuating between 4k and 8k per blob. The drop rates actually influenced the value so people's "stock" actually went up and down. The reason for this diatribe is to illustrate that a token with very little in game use (it just makes more dramatic looking armour) was used as an alternate unit of currency alongside the standard gold/platinum with it's own recessions and exchange rates!