This one recently came up in conversation: "Daylight saving time was meant to help farmers."

From the Washington post a few years ago,  "In fact, the inverse is true. “The farmers were the reason we never had a peacetime daylight saving time until 1966,” Downing told National Geographic. “They had a powerful lobby and were against it vociferously.” The lost hour of morning light meant they had to rush to get their crops to market. Dairy farmers were particularly flummoxed: Cows adjust to schedule shifts rather poorly, apparently."

And the are more persistent myths.