I've seen many pics of sunflower fields and they fascinate me everytime! Your pic is a really good one. I love the light and the warm colors of the sunset. It really fits to the yellow sunflowers. The composition is very nice. The field is about 2/3 of the image and the awesome sky is 1/3. You chose a good focal length to get that wide view which makes the field look gigantic! Also the angle is great. You also achieved a very balanced exposure between the sky and the field which is not easy. None of them is either too bright or too dark! Well done! The picture is also very sharp almost from the very front to the back! All in all it is a great picture!