Menelluin is the Elvish name for "cornflower".
It was the emblem of Idril Celebrindal, is stated to be an inlaid plaque saved from Gondolin and descending through Eärendil and his son Elros and influenced Númenórean circular designs. The Emblem was taken to Gondor by Elendil.
Etymology
The word menelluin means "sky-blue"[1] in Quenya (from menel = "heavens, sky" and luinë = "blue").[source?]