Michaelmas, the feast of Saint Michael the Archangel (also the Feast of Saints Michael, Gabriel, Uriel and Raphael, the Feast of the Archangels, or the Feast of Saint Michael and All Angels) is a day in the Western Christian calendar which occurs on 29 September (Wikipedia)
Michaelmas Daisies or Asters are in flower at this time of the year so the flowers are associated with the start of autumn in the northern hemisphere. They come in colours from pale blue to deep lavender, pinks, mauves and white and the bees and butterflies love them.
Asters
Blue and Yellow
Pretty in Pink
Earth laughs in flowers 
I can’t imagine not having asters in the fall…they are so beautiful and I love how the bees+ butterflies just dance all around them this time of year…I love that “humming” this time of year!