"When I graduated from high school in 1962 she told me, 'Take care of this, boy, I lost mine,'" said her son, Ed Reeder.
Rosa Reeder died on Thanksgiving Day, 1995. She never found the ring.
But on Tuesday, Matt Carroll took his metal detector to a dirt lane along a hill near his Boonsboro home. While meandering along a path, just trying to kill some time, the detector hit upon a gold ring.
A class ring, it turned out. From Boonsboro High School, Class of 1937. With the initials "R.L.G." inscribed inside.
"It looked like a woman's ring because it only fit on my pinky," Carroll said. "It was in pretty good shape."
Determined to return the ring to its rightful owner, Carroll took it to the Boonsboro Amoco station and told an employee there about his find. The employee called his grandmother, who remembered a woman named Rosa Gilardi from high school and knew her married name was Reeder.
Carroll had met Ed Reeder a few years ago and the two became pals.
Carroll called Reeder's daughter-in-law at work to make sure he was the same person. When he got confirmation, Carroll invited Reeder to his home.
"I was getting stuff at Amoco - lottery tickets - and my cousin said, 'Hey, Matt wants to see you. He found something that might interest you,'" Reeder said.
"I told him to come up (to my house) because I wanted to see his face when I gave it to him," Carroll said. "Even before I showed him, he said 'You found her class ring.' It was quite a moment there."
Reeder is still stupefied at Carroll's find. As a child, Reeder had played over the same area where his mother's ring was found.
"For him to find that, you're looking at over 50 years," Reeder said. "That ring has laid there a lot of years. She'd have been ecstatic."
It wasn't the first time Carroll found treasure with his detector, but it is the first time he found an item with such sentimental value. He didn't even consider keeping it.
"When I find something like that, it belongs with the owner, or the owner's son. I'd do the same thing again," Carroll said.