Mine enjoyed Gourds. We had them piled high in the house through the winter, after harvest. You might need a plan for how they get disposed of without a rebellion though!
Mine love Carrots and Sweetcorn, so we grow lots of them. The kids didn't really grow them, but they do get involved in the harvesting. We grow carrots in pots (half old used potting compost, half sharp sand) and they can just pull the carrots they want as the soil is so light, and I bring the next-pot-to-harvest into the conservatory so the youngest can be sent to "get 5 carrots for lunch" without having to go far
Now they are a bit older they help with the seed sowing, and the planting out, just working alongside me. They get bored reasonably quickly, so I only ask them to do a few, and I pull their leg mercilessly through the rest of the growing season about how crooked their rows were ...
I encourage them to enjoy the harvest - they know that our veg taste amazing compared to what they get at school and at other people's houses ... so they are learning the benefit, and most of what I know about veg came from reading and doing, even though lots of adults gave me good advice when I was young - so I think all you can do is to create a future interest - otherwise they will see it with as much joy as doing Latin Vocab!
Make sure they understand that numerous plants are poisonous too. Mine are aware that we can pick Aconites and it doesn't kill us! but that we should wash our hands as soon as we come in. I don't want them becoming over-anxious about it, but equally I didn't want them just shoving everything they saw into their mouths when they were little.