Michaelmas was the celebration of Michael's victory over Satan.
Michaelmas was normally the day by which all harvests were in. A reeve would be elected to take accounting of the harvest so that it could be prepared for the lord.
Michaelmas was one of the quarter days along with Lady Day on March 25th, Midsummer Day on June 24th, and Christmas on December 25th when rent was due. All debts had to be settled on the following quarter day.
A typical meal was a goose and a special cake called a Struan Cake, a St. Michael's Bannock, or a Michaelmas Bannock. Nuts were traditionally cracked on this day. It was believed that blackberries couldn't be eaten after Michaelmas because Lucifer had cursed them after he had landed in them.