What's the noun for flaxseed? Here's the word you're looking for.
flax
A plant of the genus Linum, especially Linum usitatissimum, which has a single, slender stalk, about a foot and a half high, with blue flowers. Also known as linseed, especially when referring to the seeds.
The fibers of Linum usitatissimum, grown to make linen and related textiles.
The flax bush, a plant of the genus Phormium, native to New Zealand, with strap-like leaves up to 3 metres long that grow in clumps.