The Rudbeckia flower in this photo is from a 10-year-old plant which comes back every year, regrowing from the ground up.
The disk of the flower was approximately 3″ (7.5cm) in diameter.
When I looked carefully at it with my unaided eye, I thought the green feature was the center of the flower. However, when viewed through the lens of my 100mm macro lens it became clear it was an insect – a very small green mite.