Coumarin: C₉H₆O₂

From: wikipedia.org

Coumarin is a chemical compound (benzopyrone); a toxin found in many plants, notably in high concentration in the tonka bean, woodruff, and bison grass. It has a sweet scent, readily recognised as the scent of newly-mown hay, and has been used in perfumes since 1882. It has clinical medical value as the precursor for several anticoagulants, notably warfarin, and is used as a gain medium in some dye lasers. The name comes from a French word, coumarou, for the tonka bean.