Once food is stable, build a Market Stall. Assign a rat with high charisma as a Merchant. Now, you need to close the loop. Create a Treasury building. The ruler prints coins here. Give each citizen a "Stipend" (Universal Basic Income) of 2 coins per day. This jumpstarts the economy. They take the coin, buy mushrooms, you tax the coin, and you use it to pay the guard.
