Beautiful quilt!!!!!!!!!!!! I'm not sure that a garbage bag would be sturdy enough. A strong plastic almost a vinyl would probably be better I think. Probably a pin would go through either one, but the heavier plastic the better. If the box would become damaged at least the quilt maybe wouldn't. Maybe check with Fed ex or Ups even the USPS might know. I'm alot of help. LOL Good Luck in the show!!!!!!!!!!!!!