You didn't say what speed you are running the game at.

Is the two hours until the next crop at 1/2 speed, normal, or 2x speed?

The food will run out faster at 2x speed than at 1/2 speed, but the crops will also come in faster, so it is a balancing act. (I haven't worked out how often the villagers eat without walking over to the food bin.)

First thing is to keep looking for those mushrooms! You may get lucky and find some red ones, they are worth more. Also, do you know about putting the game on pause and then piling on all the kids on top of one mushroom? When you do that, all the kids that successfully bring his/her mushroom to the foodbin will get credit.

If you are running at 1/2 speed, you may want to (for a short while) switch to 2x speed. The two hours will reduce to ~1/2 hour and while the villagers will eat more, it'll ease your nerves once those crops come in.

If the bin gets really low, then you may want to set the game on pause, and search for mushrooms that will still popup. That will take longer for your crops, but it'll be some extra food for your villagers.