hi Kathy,
even if you don't have a refrigerator handy, if you pack the lunch in an
insulated bag, and put in one of those cold pack thingies, it'll be OK by
lunchtime. pack carrot and celery sticks with nut butter for a dip, or you
could bring vegetable soup in Tupperware if there's a microwave available,
chicken drumsticks, leftover cooked roast beef, hardboiled eggs, deviled
eggs,  salad, and the ever-popular trail mix.
sometimes i freeze a plastic water bottle (don't fill it all the way), and
use that for a cold pack, and then i have ice water to drink because it will
partially melt by lunchtime.
hth, JoAnn.