ooOOOoooh tough one haha but yeah, i would have done the same, done it many times with stuff i have found like that!
My instant karma one day…. I had found a brand new iphone on the train so i called the “home” number and said i would post it back so i did, well later that day i left my wallet on the bus, it had £780 in it as i had just left the arcade…. i was £900 in to a machine and managed a comeback of £780 lol but anyway, back to the bus, i left my wallet on the bus and as it set off i realised, luckily it got held up at lights and i was able to get back on, found my wallet where i had been sitting….. cash gone! Bastards! It had been the last stop where i and everyone else had got off so basically, someone saw me leave it behind, said fuck all and swiped the cash!