I think the best way of starting a farm essay is to tell a story. You can either tell a typical morning or a typical day of your life on the farm or tell a story of a dramatic event like the birth of a calf or a difficult time with crops or weather. The story you tell should relate to the meaning you want to express to the reader at the end of the essay. For example, if you want to explain how living on a farm has made you an independent thinker and able to deal with a crisis effectively, you can start with a story that shows you doing that, or shows a time when the circumstances forced you to develop those character qualities. If you want to explain the beauty of living in nature on a farm, you can tell a story of what it is like to see the sunrise each day, or tell what it is like to walk along the land of your property and explain in vivid sensory detail what you see, hear, smell and feel.