When the green velvet curtains first show up, they're connected for Scarlett to her mother, Ellen, and to her comforting childhood. Check it out:
The moss-green velvet curtains felt prickly and soft beneath her cheek and she rubbed her face against them gratefully, like a cat. (32.61)
But then suddenly, Scarlett realizes that she can pull the curtains down and turn them into a new dress, so that she can go to Atlanta in splendor and convince Rhett to marry her and pay the taxes on Tara so she won't lose the land.
The curtains, then, are one of Ellen's last gifts to Scarlett; she wears her mother's curtains to save her mother's house. But at the same time, wearing the curtains in order to shamelessly attract a manâand not necessarily even for marriageâ is a betrayal of her mother's ladylike code of behavior. She's not so much using her mother's memory as defacing it. So the curtains are a symbol both of Scarlett's ingenuity and of her betrayal, and also of how she has to betray the past in order to save it. The curtains are both her pride and shame.
At least she remembered to take the curtain rod out of the dress before she went to see Rhett though. There's embarrassing and then there's embarrassing.