You did the right thing, you saved someone hours or worrying and calling around to get new credit cards and ID.
I used to joke about finding a bag of money and keeping it until I read about some lady who returned $10K she found and it turned out the money was for some kids charity. If someone had kept that money how shitty would that have been?
You never know how badly someone might need their wallet or money.
Even a few hundred bucks is a lot to some people...