Wall Of Sunflowers

I have a wall of sunflowers dividing my garden in two. In May my daughter planted an entire raised bed with seeds saved from sunflower heads from the previous year. In little over 3 months these have grown from nothing to over 2.5m tall. I'll be saving some heads for next year and even have a few neighbours and friends look for some too.

Anyone know if ordinary ornamental sunflowers can be harvested and the seeds roasted for use as a snack? I also hope to keep some harvested heads for use as bird feed over the winter months.