I bought these super cool bento boxes at Pottery Barn Kids and I absolutely love them! It's always a chore to figure out what to put in my kids lunches but for some reason, these containers make it easy because each compartment is good for different things (a fruit, a veggie, a snack, a main and a little surprise in the closed section). These are great because you can keep everything separate (for those picky eaters who don't like it when things touch!) and you don't have to wash a bunch of different containers after.
My kids are big fans of rice (gohan) and seaweed (nori) so whenever we have leftover rice, I make Japanese rice balls. In Japanese they are called onigiri (おにぎり) and come in oval or triangular shape as well. Most onigiri are made with a filling like salmon or Japanese pickled plum (umeboshi) but I make mine plain because I know those are a sure win with my kids. I use my handy-dandy plastic mold that you can get at most Japanese grocery stores. If you don't have one, you can easily form them by hand. I take leftover rice that's been pretty well hydrated. If your left-over rice didn't stay sticky, you can always cover it with a wet paper towel and nuke it for 1.5 minutes or so, then it should be back to it's sticky state again. I line my plastic onigiri mold with saran wrap and push the rice down into it until it's firmly packed. Then I put the top of the mold on and press down. I remove the top and pull up on the sides of the saran wrap and voila - I have perfectly shaped little rice balls all ready to be wrapped up and saved for lunch! I add some crispy nori squares (recipe in my "just roll with it..." blog) and my kids are happy as clams at lunch time. If you want to throw some protein or veggies in there, you could add tiny little bits of chicken, turkey, spinach, cooked carrots or edamame into the rice before you put it in the mold. These are great for picnics, beach outings or for a healthy after school snack. My kids call them little nori tacos!