Once when I was helping in a Kindergarten class the students dug up carrots they had planted in the yard and cared for. They were absolutely amazed to see the results from the tiny seeds.
As a child I loved eating the peas from our garden and my grandson was proud to dig up potatoes from our yard and help pick zucchini from the vines.
Besides helping children learn about nature and science, letting them plant, care for and harvest vegetables can have another advantage. Sometimes picky eaters who don't like veggies are willing to eat those they've grown or helped to grow themselves.
Of course vegetables are not the only kind of plants in gardens. Watching seeds or bulbs develop into flowering plants can also be exciting for kids. And, to be honest, gardening can be a good excuse for children to play in the dirt.
In urban areas many people don't have yards, but container gardening on a deck or rooftop or even using flower pots can help children learn about how plants grow.
Where I live, in the Sierra foothills of northern California, it's pouring rain today and it won't be time to plant gardens for quite a while. But there are lots of areas where it actually feels like Spring.
Wherever you live, if you have children it's a good idea to let them experience the joys of watching plants develop.