Turning my parents' lawn into a garden

Hey Y'all,

I'm setting up to get a garden going on my parents' lawn...

They are the type that buy lots of processed foods, are pretty ignorant about what work goes into their produce. The great thing is that they are pretty open to me doing this.
I'm looking for a good, short explanation of what's wrong in the food industry. Of course, youtube offers tons of videos, but if anyone knows a good one in particular, that'd be really helpful.

Planting eggplant, lots of different varieties of tomatoes, sunflowers, potato, corn, red peppers, parsley, cilantro, onions, chamomile, lavender etc...

The trees in the picture are a big oak tree and two mango trees. The smaller tree in the other picture is an orange tree.

If I cover my lawn with cardboard, will it kill the grass underneath?
Are there any bed configurations that are especially good for these vegetables?
What are some elements that can increase biodiversity?
What can be done with a small spot that floods? It has an area of about 4 cubic feet

So far, I'm doing this completely by myself, so any help would be appreciated.

Monica Rocha wrote:
What can be done with a small spot that floods? It has an area of about 4 cubic feet

Plant some taro. You can find corms in the produce section of Asian grocery stores. The leaves can be used to make callaloo, and the corms can either be boiled to make poi or sliced and deep fried to make taro chips.