"Eat. Spit. Be Happy." says DAVID, a manufacturer of sunflower seeds. I can't agree more. If not for the fact that I've been trying to teach my children not to spit, these would be a perfect snack.
Once you get the hang of eating them, sunflower seeds are a great snack. They have 84% of your daily allowance of Vitamin E, and lots of other nutrients that your body needs. They are roasted with oil and salt and that's it.
You can find them at any convenience store in small bags next to the nuts. If you are driving, you need to get a paper cup to spit out the hulls. This can take some practice, so don't get too upset if you find yourself with drool down your shirt.
The fact that you must get the seed out of the hull with your teeth and tongue means that you have to work for your snack. This will slow you down, so if you are watching your weight, you will eat less.