Michaelmas daisies for Michaelmas Day.  29th September is one of the “quarter days” in the year and was one of the dates when new servants were hired or land was exchanged and rents were due and debts were paid.  It used to be a time when the harvest was expected to be completed  (it hasn’t been finished yet around here) and the end of a productive period before the next farming cycle began.  Generally the day is no longer celebrated as it used to be and has evolved to become a Harvest Festival celebration in churches and communities.
According to legend the Angel Michael defeated the bad angel Lucifer who was so angry when he fell into prickly bramble bushes that he spat and cursed them making them spoilt if picked after the date that he was thrown out!   Michaelmas also meant eating goose. A goose fattened on the stubble after the harvest was gathered would be eaten to protect the family from poverty for the next year.  “Eat a goose on Michaelmas Day and want not for money all the year.”  When Queen Elizabeth I heard about the defeat of the Spanish Armada in 1588 she was feasting on goose so apparently she decreed that goose should be eaten on Michaelmas Day.  Sometimes September 29th was called Goose Day and Goose Fairs were held but the hiring marts are now no longer used and instead are more like funfairs.
St Michael is celebrated as a protector from darkness and evil as he defeated the evil Lucifer or Devil. These Michaelmas daisies show up as lights against the relatively dark leaves of the hedge.