Saw this on reddit the other day, thought maybe someone here could find it useful as well. Managed to find a few hundred dollars for my cousin. Some of the state's websites looks sketchy, but they're all legit.
https://www.reddit.com/r/AskReddit/...s_surprisingly_not_bullshit/d3zit3m?context=3
"Every U.S. state holds onto money that people are owed and haven't claimed. Including from third-parties. You just have to go to their website and look yourself up. I got $500 from a computer company I bought a laptop from once, and a few other small payments too.
Start here and don't forget to look at "Search by State." You may not have anything coming to you... but you might!"