Oh that is beautiful. Is that the mammoth dill? I love that one. I had new seedling come up this year but they were in an isolated area where the dill was last year. When I harvested the seeds, I let a few fall to the ground just for that purpose.
I see you have some seeds ready to harvest there, the dried ones, that is if you want to harvest them. I find it is easier to take a brown paper bag, or catching recepticle and put it under & around the seed heads. Then just take your hand at the base of the flower head and push the seeds into the bag - they should fall off easily. They are good for cooking and pickling and planting or trading seeds too! Just store them in an air tight jar.
Also, if you do much pickling, the greener flower heads can be cut and added to pickling vinegars for a pretty look, plus flavor.
One plant does give you more seed that you could need!