We thin plants to 12 inches apart for short varieties and 18 inches apart for tall varieties once plants are 4 to 6 inches tall. Corn planted too closely may offer a smaller yield. Here are some varities that don't grow over six feet: 'Little Indian', 'Baby', 'Golden Midget' (butter yellow kernels), 'Glacier' (white kernels), 'Miniature Hybrid', 'Baby Asian', 'Baby Blue' (blue kernels), Bo Peep ('pink kernels'), and 'Strawberry Popcorn'.

Here is a link that might be useful: HarvestToTable.com

Corn has pollination problems if it's grown in too small of a group, 4'x4' may be inadequate, resulting in ears where only every other kernel develops. Corn is also very cheap at the store.

For a kid-pleasing garden I like strawberries and snow peas. Could also try ground cherries.

You could try to do a bit of hand pollination, but it would not be worthwhile.

Easy to grow would be tomatoes, root crops, brassicas, lettuces, sunflowers.

You might want to consider popcorn. I grew a patch that was 4 x 4 feet and planted one per square foot (16 plants). I was worried about pollination, but they were fine. Unfortunately, the good pollination from a small number of plants may be dependent on the variety and Cochita Pueblo (the variety I grew) is not available this year. I think kids would really like it: it's beautiful and can be eaten.

{{gwi:40740}}

Maybe Strawberry Popcorn would work. It is a pretty small corn:
Strawberry Popcorn

Or, maybe Tom Thumb, a very small popcorn that could be planted as you originally planned:
[Tom Thumb](http://www.seedsavers.org/Details.aspx?itemNo=864(OG)

Bellatrix