My DS (3.5) has sandwiches in his lunch, what else would they take on a packed lunch!
He takes to nursery for his lunch, cheese sandwiches (occasionally jam as he loves them), 2 small yoghuts, a pot of strawberries (the only fruit I can guarantee he will eat), if he has jam sandwiches, then he has some cubes of cheese, a pot of breadsticks and occasionally a jam tart if he has been really good (its his new favourite thing). He is fussy and pretty much has the same thing at home for lunch every day. Sometimes he goes through a grapes phase so I can cut some of them up for him with his lunch and he now likes golden delicious apples that are pealed and chopped up so he has that for a snack sometimes.
He has only just started liking sweets, he used to spit them out, so he has them at parties of if my nan has some at her house. We give chocolate as a treat and thats after tea if he has been well behaved. If he is on a roll and is being very good then he will get it most days after tea but it is a few buttons or chocolate stars from a pack, not much. Sometimes he will have a mini milk after tea or a jam tart or if we have been baking, then some buns or cake if he has been to a party. He rarely has crisps, he would eat them more but I don't given them often and then its usually half a pack on a plate unless we are out and I give him that as a treat. MacDonalds fries are a rare treat, they are the only chips he will eat and sometimes I can't be bothered to cook tea so we go to MacDonalds.
Luckily, he has taking a liking to bread and butter and thinks this is a great thing to have with or after his tea! He also likes cracker bread which I will give as an inbetween meals snack. Breakfast is always cheerios or shreddies, its the only cereal he likes. Sometimes will have toast and jam for lunch and Saturdays often has a croissant if DH has been to the shop with him.
I thought he wasn't that healthy and we give too many treats but actually looking back at that, it isn't bad.