This Massachusetts NBC affiliate WHDH article
shows why it's important to document your savings bonds. A woman had given away a hope chest and other items from her late mother. It turned out that the mother had stored her savings bonds in that hope chest. Fortunately, the junk removal worker found the bonds and returned them to the woman.
The bonds didn't have any value for the junk removal worker. He would not have been able to redeem those bonds if he had decided to keep them. If those savings bonds didn't have a beneficiary listed, then according the TreasuryDirect
If only one person is named on a savings bond, and that person is deceased, the bond becomes the property of their estate.