The brown wallet containing a one pound note, stamps worth 18p and receipts from 1987 were found at Old Market Hall, in Matlock, on Tuesday.
Council staff made the discovery at the back of a disabled toilet cistern inside the building and alerted Derbyshire Police officers.
The force has now posted an appeal on social media in the hope of reuniting the lost property back with its rightful owner.
It is believed the wallet may have some connection to the Adkin family, who lived in Victoria Court in Matlock.
Matlock, Cromford, Wirksworth and Darley Dale Safer Neighbourhood Policing Team posted on Facebook: "We need your help.
"This wallet was handed over to the Matlock Safer Neighbourhood Team by Derbyshire Dale's District Council after being lost in the building and for about 35 years.
"We are trying to identify whether there are any members of family of this gentleman still living in Matlock to get this wallet back to them as it contains some rather interesting and old memorabilia.”
They added: "Does anyone know of a Cyril Adkin or Jill Adkin that used to reside at Victoria Court, Matlock?
"If anyone feels that they may know of any family members please send us a message. Thank-you."
Several people claiming to be family members replied to the post and the force said enquiries were still continuing.