You can use squash and shred it like pasta. you can use cauliflower like mashed potatoes. use lots of veggies in things like spaghetti sauce. You can make vegetable lasagna with I think squash again as the pasta.
(how to make squash noodles)
http://summertomato.com/better-than-pasta-subtitutes-summ...
http://allrecipes.com//Recipe/baked-spaghetti-squash-lasa...
One of my kids (they are 2 and 4) favorites is pic de gallo... corn, avacado, black beans, poblano pepper, cilantro, tomato, celery, with some garlic, salt and pepper and lemon juice. so good, we eat it on top of rice, with a little bit of shredded chicken, and some shredded cheese.
They love the way I make veggies. I usually do this with asparagus (cut into about 1 1/2 inch pieces), carrots, squash, fresh green beans... I usually only make one at a time though:
Put a little bit of olive oil in pot, add in about 1/4 (or less) of onion and stir for a minute, add in cut veggies, flavor with a little bit of salt, pepper, garlic powder (or fresh minced garlic), and if you need, just a small dab of smart choice butter. I then give them a few pieces at a time and a little bit of Girards Light Ceaser dressing to dip if they need an extra push.
Roast with carrots, celery and potatoes is a big hit and easy.
You can also make fruit smoothies... add in spinach or carrots to the fruit mix and a little bit of sugar to help with the tartness.
My kids also love corn, I just heat it up, add some salt and pepper and a small amount of butter.
You can add veggies to tuna salad or chicken salad too and put it on a little roll.