Lilies

Large flowers that grow on slender stalks, that in Middle-earth were found at least in the Gondorian lands of Lebennin and Ithilien. In the modern world, lilies can grow in a variety of colours and patterns, but in Tolkien's world they're always referred to as being white: for example in the description of Éowyn in her illness as 'white as a lily' (The Lord of the Rings V 8, The Houses of Healing). Among Gandalf's amazing array of fireworks was one in the shape of a lily, which could famously hang in the air throughout an entire evening.