Plants that humans eat are literally some of the most widespread plants in the face of the Earth. Apples, tomatoes, potatoes, corn, soy, and rice are all massive successes for the plants in spreading, that doesn't even get into sugar producing plants. This started as humans eating and distributing seeds. Farming just made this process not need to involve eating. It's not just about delicious either. We eat some bitter and spoiled (butter, beer) foods for nutritional value.