Answer: Maybe it's ripe?
Sunflower seedheads begin to mature by bending downward; the back of the head will also begin to brown. Cut off the head plus two inches of stem and hang upside down in a dry, well-ventilated place such as an attic or garage until fully dry. (Protect from critters or they will steal them.)
Experiment a bit to see what works best when to to get the seeds out. Some gardeners rub two heads together or use a wire brush. Then spread the seeds out in a thin layer until fully dry (test by crunching one between your teeth). They can be stored in an airtight container.
If you want a salty tasting sunflower, soak them overnight in a strong salt and water solution, then bake in a very slow (200F degree) oven until completely dry again, but not browned.
If you don't plant to eat them, you can leave it alone on the plant and the birds will eat them for you.
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