The holder of this coin is entitled to 2-3 hours of gardening, [...]
This reminded me of time-banks.
It was used a lot in South American cities, at some point during the economic crisis of 2008. In practice it was working like this: people would declare in a sort of ledger what they can do and for how many hours, as well as what they needed and for how many hours. Everybody's time was equaly valuable, no matter what they did.
It was going so well that they tried to accomodate stuff that would not fit in the time category, like renting a house. So they printed some sort of "contracts"/"money". Government and mafia, printed counterfit and the project never recovered since.
(It's been quite some time since I looked into this topic, so if I don't remember something accurately, please let me know)