You could take Clif Bars or Power Bars. YOu can also bring along baby carrots and celery sticks. And perhaps string cheese or stick cheese; anything that can stand heat and be away from refrigeration for a long period of time. I enjoy cheese cubes and crackers.
Hey why not buy a Lunchable meal and take that? Just make sure like I said it will still be edible if it's out of refrigeration for any length of time.
There's also fruit like apples, bananas, etc. just use your imagination! =)