Possibly one of the four great pagan festivals of Britain, Lammas was known as the Gule of August in the Middle Ages. In medieval England, loaves made from the first ripe grain were blessed in the church on this day—the word lammas being a short form of “loaf mass.” Lammas Day is similar in original intent to the Jewish Feast of Weeks, also called Shavuot or Pentecost, which came at the end of the Passover grain harvest. A 15th-century suggestion was that the name derived from “lamb” and “mass,” and was the time when a feudal tribute of lambs was paid. Discuss
Source: The Free Dictionary