Pocket it, and if someone comes in asking after it and you believe it's them, pay them back.
I tend to find wallets, about one every six months. The first one in recent years was on a train on the way to work. There was about $700 in there, and I was a bit short of cash at the time. Well, I thought to myself, let's see what sort of person has seven hundred bucks in their wallet. I looked through, and it was a university student. Bugger, I said to myself, if it were an acccountant or a lawyer, I could take the cash without guilt. But it's probably her bond on a new flat, or her month's pay from waitressing or something. So I went to work and called the cops.
"We can't come to pick it up, we're too busy, can't you come in?"
"No, I'm working a double shift at work today, the other chef is off sick. So I couldn't come in until this evening. She'd get her cash back of course, but would probably have cancelled all her cards by then."
"Hmmm."
"Well surely you guys come in here regularly anyway? It's a shopping mall, you must come here to pick up shoplifters and stuid kids lurking about ten times a day."
They seemed unamused by this comment.
They came along and I handed it over. That afternoon we got a call from the cops, the woman wanted to contact us. Well that was fine by us. She wanted to reward us, my woman suggested she take us out for some drinks. We went, and met her and her fiancee - it had indeed been the bond on the flat they were moving to together, and all her savings. There had also been in her wallet a piece of paper with a number on it - at first I thought it was a phone number, but it was too long. It turned out this was the number for her mother's credit card, which she also had in her wallet. So if someone else had scored it they could have really gone sick with it.
On another occasion I was walking down the street from having lunch with someone, and passed some public housing units. There in the gutter was a wallet. It had $150 in it and about half a dozen Medicare cards in different names, all vaguely Arabic or possibly Somali. Probably someone scamming Centrelink and drawing several different benefits - but how would I know? Again, I was a bit short of cash at the time, but if the guy was living in public housing and was Arab in racist Australia he was having a harder time than me, that's for sure. I dropped it off at the cop shop, a few hours later I got a call from the cops.
"We have the owner here, he says there was more cash in the wallet before he dropped it."
"What the fuck? If I were going to take the cash, I wouldn't have left $150 behind and then dropped it into the police, would I?"
"Yes I know but he's standing here screaming and I had to ask."
"Tell him to go fuck himself and I hope next time he loses his car keys and it gets swiped, too."
The cop laughed and hung up.
There have been another four or five wallets and purses, I always look to see who owns it. Unfortunately it's never anyone I'll feel no guilt in taking stuff from, it's always some student or pensioner. Why aren't bank managers and used car salesmen more forgetful and careless? Bastards.