Evening Primrose Oil
This pretty yellow flower was used as a poultice by Native Americans to help bruising and swelling; in the 17th century, it was introduced to Europe and became a popular folk remedy, earning it the name king's cure-all. In more recent times, it’s the seeds that are used to extract oil, which contains high concentrations of unsaturated fatty acids. These include omega-6 fatty acids, linolenic acid, and, perhaps most notably, gamma-linolenic acid (GLA). GLA is a preliminary stage in the production of prostaglandin, a hormone-like lipid compound (fat) that is essential for the proper functioning of a cell. Prostaglandins regulate inflammation, cell growth, and hormone balance, among other functions. This makes it a great treatment for hormonal acne and eczema.  There’s also some evidence that the oil increases skin elasticity and firmness.
Find it in
 Ziboh, V.A. (2001). "Gamma Linolenic Acid: Recent advances in biotechnology and clinical applications". The American Oil Chemists Society.
 Kapoor, Shweta, and Swarnlata Saraf. "Topical herbal therapies an alternative and complementary choice to combat acne." Res J Med Plant 5.6 (2011): 650-9.
 Horrobin, David F. "Essential fatty acid metabolism and its modification in atopic eczema." The American journal of clinical nutrition 71.1 (2000): 367s-372s.