I agree that the OP dropped the ball here in regaard to not taking the receipt for the dress she had JUST purchased. You didn't take your purse? Isn't that where your license normally is? And how did you pay for your items? Unless it was cash even the receipt may not help - the refund would go back to the card you used.

As far as driving without a license - that is entirely different than not having your license physically available. Driving without means you do not HAVE one, period. If you don't have it on you and get pulled over, give the cop your name and address. They can look it up right in their car. And since I think all states now have photo licenses it's not like you can give someone else's name. It's a good idea to always have your license on you when you are driving, but it's not critical.