There are many benefits to eating locally grown/seasonal food. It can be cheaper and it helps the local farming community's economy. Historically, farming was all natural and there were no artificial fertilizers and pesticides being used to produce food. As the demand for food production grew, companies began producing food in unsustainable ways. Another reason for this would be for transporting food over long distances.
When you go to the grocery store and buy locally grown food it not only helps the community, but it also tastes a lot better, and it saves money in the long run. For example, when I lived in Hawaii I started with buying non-local grown pineapples from grocery stores, but I soon learned that buying locally grown pineapples from the local stores were a lot cheaper in price and tasted a lot better. In the end, not only is locally grown food a lot better tasting, they also help keep us healthy.
The chart below shows what particular produce is grown depending on the season.