Sunday Afternoon

After this spiraling explosion of color drops away, the plant is left with a dull grey cone, which I have often seen without guessing where it came from. This is the first time I found the flower, and I got lost in the delicate pattern. Then I spent some time googling and ended up reading about Fibonacci numbers, multiplying rabbits, the curve of a nautilus, and the optimal packaging of sunflower seeds in neat spirals. Lovely diversions, but what is the name of this flower?