Add Yahoo as a preferred source to see more of our stories on Google. bowl of sunflower seeds surrounded by more seeds - Sergeyklopotov/Getty Images Sunflower seeds may look hardy, but like all nuts ...

Sunflower seeds may look hardy, but like all nuts and seeds, they're rich in oils that eventually go rancid. When those oils break down, the signs are hard to miss. The most obvious clue is flavor, as ...