Cultivated flax used for edible products (oil, fiber) is Linum usitatissimum.

You can eat the seeds but, only if they are ground into a flour as humans are unable to digest the whole seeds. You can also consume flaxseed oil which is VERY good for you and rich in Omega-3 and I believe Omega-6 Fatty Acids that are normally found in fish. These Fatty acids actually help to reduce Choleserol and have other health benefits.

Oil goes rancid quickly in ground seeds or oil; I grind mine in my herb mill (electric 'coffee' grinder) & store in the freezer in a small jam jar. I start with about a Tbsp of milk thistle seed (grind that a bit first) then add about 2 Tbsp of flax seed, grind that a bit; & then sesame seeds to fill the hopper. I usually add about a teaspoon of fennel seed before the sesame seeds, to aid digestion.

The sesame seed hulls are high in calcium, (1/4 cup ~ the daily allowance of calcium) & the milk thistle good for the liver.

Several herbalist friends suggest sprinkiling the flax/milk thistle mix on your morning cereal or on salads, rather than taking oil or capsules. The milk thistle seed coats can irritate some folks stomachs - so you need to see if this works for you.