There is a website run by National Association of State Treasurers called MissingMoney.com.
It is a searchable database made to reunite owners of lost accounts with funds being held anywhere in the USA. I put in my name and found two entries. Within about a week, I had a check in my hand. I have told many friends about the website and they have thanked me for hundreds of dollars being returned to them.
Try it for yourself, your relatives and friends, it is a great opportunity for Hashavas Avaida.
Old bank accounts that may have still had a few cents.
From the US Gov site, other money can come from “unclaimed tax refunds, back wages, wages, life insurance, retirement pensions…” (US GOV).
A long time ago I worked at a job and never picked up my paycheck because it was a pretty evil job and I just couldn’t go back there. Sometimes I wonder what happened to that money.
Reply to Joseph: I do not know, but I saw an account with my grandfather’s name and address and he was niftar about 45 year ago. Could be it belongs to my grandmother, but that is still almost 20 year old.
The main point is that spreading word about this resource, or telling relatives about money being held, is a great opportunity for hashavas aveida.