So this is more for Margaery from A Song of Ice and Fire than for HBO's Game of Thrones because a)Margaery is supposed to be 16 not 30 and b) I loathe, abhor, despise and hate the wardrobe they picked out for Margaery in season 2. Natalie Dormer must have kicked the wardrobe designer's puppy or something because I have no explanation for how else they would have decided that The White Witch was a suitable wardrobe influence for sweet, courteous Margaery who is NOT Cersei Jr, kthnx HBO.
So, here is a lot of flower and garden-influenced themes and yes some bared cleavage but I don't entirely see Margaery wandering around the Red Keep in her underwear no matter what HBO decides to have her wear.
Lady of the Reach: http://www.polyvore.com/lady_reach/collection?id=1496010
Margaery Tyrell 2: http://www.polyvore.com/cgi/collection?id=1841665
Margaery Tyrell 3: http://www.polyvore.com/margaery_tyrell/collection?id=1878631