Larger than chia seeds, flax seeds come from a crop cultivated not only for food but also for fiber. In fact, spun, dyed, knotted flax fibers have been dated as far back as 30,000 years ago! Flax was cultivated in ancient Egypt where its fibers entombed mummies and dressed Egyptian priests. And we use it today to make linen for our crispy sheets, tablecloths, and fashionable outfits.