As the world's most expensive spice, saffron provides a beautiful yellow/golden color and pungent, aromatic flavor to foods. You can find it sold as red-gold threads or in ground form, and it is available year-round. It has been used for centuries in Persian, Arab, European, and Indian cuisine. Saffron is a spice made from the stigmas of the fall-flowering plant Crocus sativus, a member of the iris family.

Source: The Spruce Eats