Grain-based Local Currency refers both to a form of monetary unit, and to one of the earliest economic systems to supplant pure barter. In such a system, money is minted/printed to correspond with the harvest - essentially each dollar (or whatever your monetary units are called) is a share of the recent local harvest. You actually have the option of redeeming your money for wheat or rice or whatever the local crop is.
Unlike gold, the grain could rot, be eaten by rats, etc. The result was that you'd have huge influx of money into the system around harvest time, and then a rush to spend the money and get as much done with it as possible before it went bad. Hoarding cash wasn't a possibility - money you hoarded would devalue fairly quickly. So, money would be spent just as quickly, wages tended to be pretty good, and the harvest would be followed by a flurry of improvements to property and similar investments that would retain their value longer than the grain did. Money would change hands many times over a short span of days - last week I was a harvester, but this week I'm on the team that's building the new church.
Within a given community, the gaps between the rich and the poor were significantly smaller than we see today. Eventually, however, this system was undermined by the actions of Kings and Banks. National currencies supplanted local currencies, and the money became concentrated in the hands of the few.
Game and Story Use
- This makes for a radically different economy than we are used to (either in reality, or in the gold piece-based economies of gaming), where money only has value if it's spent (or if you're starving), and is worthless if you hold on to it.
- Part of why we end up with ridiculous economies in RPGs, where the local village is poverty level, but the inn-keeper owns a +3 sword that's worth more than the rest of the village combined, is because of failure to understand how the actual economic systems of history worked.
- This has some relation to the Koku (amount of rice to feed a person for a year) and a Masu (enough rice to feed a person for a day). IIRC, the Koku was presented a unit of currency in the old Oriental Adventures book for D&D (and, presumably, other RPGs with similar Far East settings).
- The local village wants to hire the PCs to save their Adventure Town from the marauding Monster of the Week. They don't have a magic sword or a pile of Gold to offer, but they can give you 30% of their next grain harvest. This is a huge sum of money, but only if the PCs can manage to turn it around, such as by exporting the grain to a land where that crop doesn't grow.
- Likewise, such alternative currencies can (and perhaps should) be a large portion of the treasure when facing Humanoid creatures. The bulk of treasure in the Orc lair logically shouldn't be gold coins, it should be smoked meats, tanned hides, foraged plants, etc. If we're talking about orcs that raid instead of forage, then the lair should include the booty they've taken from places they've raided - and again, it'd be logical for that to be more food and goods than pure gold.
- A mean GM might put out legends and rumors of a huge treasure in some old ruins, but then have it turn to be certificates for some long-since-rotted grain supply in a third location. Thanks to infestation and age, it's as worthless as Confederate Money. Tread carefully, GMs, a bit of bait-and-switch can be fun, but you don't want the PCs to feel cheated.
- This can justify all sorts of Cathedrals, Temples, Silos, Mills, Libraries, and even Fortifications in a town that looks (for 9 months out of every year) like it couldn't possibly afford such structures. They have short wealthy seasons, and work hard to capitalize on such windfalls while they last.
- Has some Red Herring potential. PCs traveling to such a town (especially if coming from another country that's on the Gold Standard) might misunderstand the source of such wealth. I could see players assuming the town had some bizarre secret, like a bargain with the devil, or a retired adventurer hiding hoards of gold. But no, they're just organized and far-sighted commoners, investing their crops in their own future.
- This can also be used as an adventure or side-adventure to gain a little (or a lot of) role-playing experience without much danger for low-level characters. The PCs could be hired by another a third party to return to a village and see that he receives exactly what he was promised. Responsibilities could include safeguarding the goods on the way to the nearest market and preventing the villagers from cheating the third party. Obstacles could include the village being under attack or already destroyed, so the group has to fight another battle; another obstacle could be a poor crop; still another obstacle could be the third party himself taking liberties with the villagers.