Hi! I have a young chilg also. Everyone learns what methods and plants work for them over time, but to make it simple, try this
Clear all weeds from a sunny garden area. Dump a few bags of compost over the area and rake it in. Place plant markers in the ground where you want each plant first, then plant your seeds around that, it is very helpful with little ones so they know where not to step.
Some of the easiest flowers are cosmos, zinnias and sunflowers. The cosmos will get bushy and produce tons of flowers, which kids love to pick. There are many different colors and varieties of sunflowers, some are giant, very fun! They attract birds, too.
Zucchini and other summer squash is easy. Melons and pumpkins just ramble all over, they are fun. These seeds (as well as the sunflowers) are big enough for kids to easily plant themselves.
Kids LOVE to pick strawberries, definately worth getting a few plants.
If you want shade, try making a bean teepee. You can take long pieces of bamboo, they are tied together at the top and spread out in a circle. Then run string around the whol thing for the vines to climb. Make sure you leave an opening to get in and out. you can use about 3 scarlet runner beans at the base of each bamboo pole. Make sure you leave an opening to get in and out. The plants get sun, but your little one gets shade.