Ugh, no don't make your kids eat white bread. It's bad for them too. Bleh.
One of my favourite lunches right now is a huge handful of baby spinach greens (pre-washed and ready to eat) and a bit of tuna on top. If I have time, I throw on more veggies to make a proper salad, but if I'm in a rush, this is just as fast as a sandwich. I usually put some low-fat dressing on it, but you could definitely eat it plain too.

I'll try to think of some more. Good luck!