When Stanley Greene’s girlfriend lost his class ring after a home economics class in 1980, Greene thought he would never see it again. Now, thanks to the help of one good Samaritan, and the reach of social media, Greene has been reunited with the ring after almost four decades.

“She was in home economics and went to wash her hands and somehow it got misplaced,” Greene said of when it disappeared. “She said she thought she took it off and set it on a cloth but you know it’s been so long we don’t really remember.”

Greene continued, “I gave it to her because that was a big thing back then … you know, the girlfriend wearing her boyfriend’s ring.” The piece of jewelry cost $350 in 1980, approximately $1,000 in today’s money when adjusted for inflation.

“That was a lot of money to us back then and Mr. Walker (the janitor who found the ring; Greene does not know his first name) worked with my dad so that’...