Single-Herb Tinctures › Oat Seed Image 1 of 1 Oat Seed from $12.99 Milky Oat seed (Avena sativa) is the seed of the common oat plant harvested in the “milky” stage. Size: Select Size 1 ounce 2 ounces Quantity: Add To Cart Added! Milky Oat seed (Avena sativa) is the seed of the common oat plant harvested in the “milky” stage. Reviews Reviewer Name Review Date Star Rating Description Posted on Etsy Product Show More