In 1973, a teenage Debra McKenna accidentally left her future husband's ring in a department store in the US town of Brunswick Maine, Sky News reports.

Fast forward 47 years and it has been found by a sheet metal worker - buried in a Finnish forest.

Ms McKenna, 63, lost the ring in Portland when she was a student at Morse High School, the Bangor Daily News reported.

The ring, which had engravings identifying the school, belonged to Ms McKenna's late husband Shawn, who she dated all throughout high school and college.

The couple was married for 40 years until Shawn died in 2017 after a six-year battle with cancer.

Shawn gave Ms McKenna the ring before he left for college, but she accidentally left it in a department store.

She said the ring was largely forgotten until the worker found it buried under eight inches of soil in Kaarina, a small town in southwest Finland.