Pasta freshly cooked in the morning, though you would have to insulate it with foil or something. It will stay warm until 1130am when I cook it at 630am. Just drain the water, and don't rinse. If you are lucky, Target has lunch bags that have a removable bottom and are quite small - I think it would fit in your jersey pocket.
For the late lunch, PB&J.
I use a rack and a trunk bag to carry change of clothes and lunch and I keep the work shoes at well....work. Do you have a significant other? You could go out for lunch once in a while and have an available pocket on those days.