I spent a while trying to produce enough beans to keep my town fed while having a surplus which I could trade for other items. At first it was fine but when a ship came in with pumpkin seeds I couldn't trade with them because my beans had a value of 0. The next ship was the same.
I am wondering why my beans are now worth nothing, I have about 4,000 in the port and I normally have about 10,000+ in my storage barns.