I ran across this website the Government provides to research whether or not you have US Savings Bonds (or Bills or Notes) that are matured. It might be a good item to check so that you don't lose track of YOUR money. Be aware that this website will only check those bonds purchased since 1974 but there is a paper form available for download to request the Treasury research those purchases prior to that date. This might be a good exercise if you have lost parents or grandparents who may have owned bonds that you have not been able to locate with any kind of a paper trail. I assume you would need to prove ownership in order to redeem them in that case.
Here you go.......
US Treasury Direct Greg