Sunflower

The detail on the sunflower is amazing. Full view is a necessity! I see that you have added some post-production vignetting, and I think it helps to define the focal point even more. The color of the blue sky is wonderful, and I think that you have a very good photo here.
The leaves in the bottom are a little bit distracting, and I would up the brightness a tiny little bit. I like the way you've defined the sunflower, and you picked the right aperture to blur the background just enough.
Maybe next time you could try an even closer shot, perhaps a macro?
Great shot.