Reward - Lost iPhone 4 in floral fabric button over case

My mum lost her iPhone at Bruce Springsteen Friday night concert, either in the stands or on the road out, it fell out of her bag, it contains so many memories and she would give anything to get it back. It was still ringing that night and the next day so we don't think it was stolen. It's a white phone but in a green/ blue floral case, kind of unusual. Any information would be gratefully received.