Sunflower patterns

Harvest of the sunflowers. Most are to be kept for the birds, coming winter (if we are advised to feed them again; at the moment, because of a contagious bird disease, we'd better not stimulate their getting together). But birds don't wait: some of the flowerheads were already mostly eaten (first picture).

For photographers (and mathematicians!), sunflowers are irresistible because of the patterns that the seeds make in the flowerhead. And as usual: patterns come out better if your eyes are not distracted by colours, so the second picture comes in black-and-white.