“Most if not all farming peoples of Europe had a tradition of gathering together for a feast to celebrate the ingathering of a successful harvest.”
I also seem to recall that the European kings of yore would declare days of Thanksgiving (feast days) for auspicious events such as an heir being born or what not. This “power” was inherited by our govenors in the new republic.
I think Harvest Festivals are something most societies have.
The Indians had one before the Pilgrims came here and the Israelites had a harvest festival too.