What if you found a t-shirt in the suit pocket — would that be theft? What if you found a registered promisory note in the pocket, still unredeemed and valid, for $50,000? What if you found a box with a bunch of cameras inside the box? Could you open the box, pocket the cameras, and then walk out of the store guilt-free since the box wasn't purchased? (Bottom line is that I agree with Dig: Whatever is in the store shouldn't walk out of the store without being purchased.)
Eh, I have no problem with taking cash. They're selling the jacket, and the jacket is still there for them to sell. You're not taking their product, you're taking something that the goodwill never even knew about the existence of. In my mind, it's just abandoned property, not part of the jacket, same as if it had been dropped on the floor.