Margaery Tyrell is a member of the House Tyrell, the second wealthiest and largest of the eight Great Houses in Westeros. She is the younger sister of Lord Willas Tyrell, the heir to Highgarden, Ser Garlan the Gallant, as well as Ser Loras Tyrell, the Knight of Flowers. You found yourself few steps from her, just she is gigantic or you are shrunk till microscopic size, so you are smaller than her finger.