I laid a sunflower bloom on a green pillow to get a sharp center approximating the same size as the next shot. Then I placed the bloom in a pot of greenery and used Blast Mode with 10 exposures on my IPhone.
I layered the two images with the blast one on top and selected the center brown circle with Shift/Elliptical marquee which constrains your selection to a circle. I feathered it with 20 pixels.
Then I added a layer mask to the top layer and filled the circle with black, bringing through the sharp center below without any other part from the bottom layer.
A few green areas needed Content-Aware Fill to make them consistent.
A square crop seemed to work well on this symmetrical image.