I usually pack them a sandwich on either a wheat roll or a whole grain bread.....turkey or bologna or something of that nature. Chips and maybe carrots....and something sweet like cookies or something. Either a water bottle or juice box or choc milk box.
My son (who's 4, also) started Kindergarten this week. He's a VERY fussy eater and will only eat a handful of things. Today I packed him an American cheese sandwich quartered and w/ the crusts cut off, a banana, chocolate milk, and goldfish crackers.