So I have been harvesting my sunflower seeds, but I'm confused about what type of seeds I'm getting. Here's why:

I planted Giants (white seeds, grew into yellow flowers) and Autumn Beauties (black seeds, grew into orange/red flowers).

Now, when I harvested a few of the Autumns, one head of seeds was all grey/white striped; the seeds from another head were half brown and half white; meanwhile the seeds from a third one were all brown!

In gathering the seeds from the Giants: One gave me all black seeds, another one half brown/half white, and another one grey/white striped!

Here is a picture of the different seeds:

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Link, in case the image doesn't show up: http://www.telusplanet.net/public/syn/pics/sunflowerseeds.jpg

Do you identify a sunflower seed based on how it looks, not on what its parent was? If so, what is what in the picture?

Is it possible for one type of sunflower to reproduce seeds that will grow into a different kind?

I did also have some sunflowers transplanted nearby that I rescued from under the birdfeeder, which I think are "black oil" sunflowers (their hulls were all black). Did they maybe cross-pollinate? I am so curious!

How should I sort these seeds so I know what to expect next year?