Accounts from State tax refunds, Estates/Insurance payouts, PayPal, Best Buy rebates, etc in different states.
Mostly due to moving, they put your $ here with the State Treasurers.

Also can search under business names.

Unclaimed
this search can be done State by State and often provides more details and where you file the claim online

MissingMoney
This can be searched for nationwide claims but if you have a common name, use above