My 8.5yo DD takes something along these lines:
1 multigrain Vegemite sandwich
1 hard boiled egg
Veggies cut into sticks: celery/ red capsicum/ cucumber
Cubes of cheese and a handful of baby tomatoes
Fruit can be a mix of strawberries/ grapes/cherries/ a whole apple or whole orange
Other ideas:
veggie sticks and a dip (like hummus)
crackers and cheese
BBQ Shapes and the like
homemade muesli bar (nut free)
tub of yoghurt (more like Jalna and less like Yogo)
dried fruit like sultanas or banana chips
I guess it worth asking what he's used to having and going from there