Omega 3's are important to many functions of the body. You can get these from fish and seafood, fish oil supplements, and tree nuts like pecans and walnuts. Flax is a fiberous plant used for many things including making fabric (linen), linseed oil as used in painting and making linoleum, and in dietary oil among other things.
Flax seeds normally come from flax plants. Flax is an oilseed just like canola and sunflower are oilseeds. Flaxseeds are rich in omega-3 fat, which helps to reduce the risk of heart disease and may even reduce risk of some types of cancer, including breast, prostate and colon cancers.