90% of people don't have a yard to grow food in.
The industrial mono-crop industry doesn't produce enough vegetation to feed america.
Not all land is arable farm land. Much of america is grass land. Grass can feed cows, not humans.

With permaculture practices you can increase the yield of your soils.
However, it is in its infancy as a process.
However, however, permaculture is often highly dependent on animals. Things like chicken tractors to turn up the soil and add important nutrients.
Permaculture may provide a path to what you desire.

Trying to have as little harmful impact on the world from your actions is noble.
But, being afraid of death is a human thing. Avoiding killing other things often has worse side effects (especially if it is a natural cycle).