Turning in lost items
If you find a lost item in a train or train station, turn the item in to a station employee or at the lost-and-found / information counter.
If you find an item worth any kind of value (monetary or otherwise) on the street, you should take the item to the nearest police station. The officer in charge will usually write a report and will ask you detailed questions about where you found the item, your name and contact information, etc. Many districts have a policy that if an item has not been claimed within a certain amount of time, you may claim the item; the officer may ask you if you'd like to have the item if it is unclaimed (depending on the item; obviously, they will not release unclaimed keys, name stamps, or other personal items), and your choice will be indicated on the report. You will then be given a copy of the report and told to keep in on file for a while.
If a lost item that is found on the street is not especially valuable (handkerchiefs, hair accessories, etc.), the most common procedure is to pick the item up and put it in a noticable location so that the owner can easily spot it if he or she comes looking for it.