Sunflower Sea by Annie Griffiths
I really like this photograph because it follows the rules of 3's. The small crop duster is pictured on the upper right 1/3 of the photograph and the horizon line is down 1/3 of the photograph. In addition, the repetitiveness of the sunflowers (because it is a sunflower field) is disrupted by that crop duster, making it a complete picture. I think this picture was taken with a smaller aperture and at a faster shutter speed because I do not see a smooth/blurred areas or focused parts. The clear blue sky balances the amount of yellow in the picture, and you can see the entire picture clearly. The photograph is clear and bright and it appears it was taken in the morning. An interesting fact about this photo is that it was actually appeared in the cover of National Geographic's March 1987 issue to cover a story about the economic struggles of North Dakota called "Tough Times on the Prairie".
You can see this picture on National Geographic's website here: