sunflowers and seeds

I have just planted some sunflower seeds to grow for my grandson and it got me thinking about sunflower seeds which I adore. I usually buy them from the health food shop but can I eat the seeds which are produced by theose I have planted or are they special varieties?

 

I think they must be varieties bred for big seeds. I have eaten my sunflower seeds but they're much smaller than bought ones so it takes too long to get them out!