Prayer of the pilgrims? Beautiful...Amen!
I'm delighted that you like it :-) Unfortunately, historians don't know which prayer(s) were recited at the First Thanksgiving. This is one that "might" have been said or something similar, as it was popular during that time. It's by George Webb from a volume entitled "Short Direction for the Daily Exercise of the Christian". It was published in London in 1625.
Sorry for not making that more clear.