Sunflowers

I'm not so sure hens will eat sunflower seeds with the shells on, fresh or dried   They don't have the right beaks for seed cracking and I'm not sure they would want to swallow the shells.  They do go wild for sunflower seed hearts, as any chicken owner who has tried to feed wild birds will testify.  Death defying stunts go on to get to them    

Sunflower seeds are very high in fat though, so not ideal chicken feed.  Maybe hang them up for the wild birds and let your hens have an odd treat of corn instead 

however do bear in mind what New Shoot has already said they are high in fat and this is not good for poultry so should be given in moderation.
Wild birds need far more calories than our hens do as they are a lot more active having to fly around to get enough food to eat to help keep them warm and survive (you can liken this to how many calories an athlete needs compared to a person who does little or no exercise).