We sincerely wish you a blessed and enjoyable Thanksgiving Day!
O God of Whose mercies there is no number, and of Whose goodness the treasure is infinite: we render thanks to Thy most gracious Majesty for the gifts Thou hast bestowed upon us, always beseeching Thy clemency; that as Thou grantest the petitions of them that ask Thee, Thou wilt never forsake them, but wilt prepare them for the greater rewards that still await.
Collect, from the Votive Mass of Thanksgiving.
Yes. Forget everything you learned. The American textbooks tell you the first thanksgiving was celebrated by pilgrims and Native Americans in about 1621. But, years before that, in about 1565, in the eldest city of this nation, St. Augustine, Florida, Catholics celebrated Thanksgiving.
In 1565, Pedro Menindez de Avilis, the Spanish founder of St. Augustine, and 800 Spanish settlers shared in a Mass of Thanksgiving. Following the Mass, Menindez ordered a communal meal to be shared by the Spaniards and the Seloy Indians who occupied the landing site.
This history can be found in The Cross in the Sand, by Michael Gannon, an expert on Florida colonial history and professor of history at the University of Florida.
And, of course, Eucharist means Thanksgiving.