There is no single office for lost property; items are usually kept where they are lost.
High value items (purses, wallets, passports, phones) are usually handed to security on the relevant campus.
Campus cards usually find their way to the Student Hub and USBs are often held in the library. In order to protect your privacy data on USBs is not accessed to identify the owner and they are held for a month before being destroyed.
Links: Campus maps