Hi mlw1980. The crops are on a timer. If you open your game after 60 minutes, you should have visible crops. If you don't open it until 120 minutes, the villagers may have picked all of the crops that were ready at 60 minutes, replanted, and the new batch will be ready whenever the timer says. Only if your villagers haven't finished harvesting all the crops will you see them when you open the game. Changing the game speed also affects the crop timer.
If you're interested, there's a discussion about the crop timers and harvesting in the VV1 Desktop (and Palm/Pocket PC) forum
here. I hope this helps.