The discovery of the beehive-shaped tombs, which date from 3,500 years ago, sheds new light on life in ancient Greece, the team behind the excavation said.
Archaeologists from the University of Cincinnati (UC) announced their findings at the site in Pylos, southwestern Greece, in Athens on Tuesday.
During an 18-month excavation, the archaeologists unearthed objects such as a gold ring engraved with two bulls surrounded by sheaves of grain, as well as a gold pendant depicting an Egyptian goddess who protected the dead.
The ring's engraving is "an interesting scene of animal husbandry — cattle mixed with grain production. It's the foundation of agriculture," said Jack Davis, head of the classics department at UC. "As far as we know, it's the only representation of grain in the art of Crete or Minoan civilization."