Not that I know of, just from personal experience. Grains kept in good condition have ridiculously long shelf life. And for commodity crops like grains, the scale of production is just so insane that it is not possible for it to be all consumed at a short time frame after it's harvested.

Also, agriculture produce's price fluctuates a lot. Farming has a long feedback time, so by the time you harvest, the state of the market is no longer the same. Anything that can be stockpiled will be stockpiled to wait for the right time. This is not normally done by the farmer themselves, but the traders. Then it's just FIFO, the oldest grains at the bottom of the silos will be taken out first.