The simplicity and stress-less-ness of Thanksgiving — as compared to Christmas, at least — must account for its great appeal, outside of the obvious food factor. Its association with and historical memorial to the Pilgrims of 1621 cannot be wholly denied, and can serve to remind us of the great stresses that were once endured in order to further simple truths, convictions, ideals, and most importantly: freedoms. There is a wealth of sources available that speak directly from these folks themselves. It seems the first Thanksgiving was, in a way, just a traditional harvest feast, complete with beer and plenty of meat (venison and game foul primarily — including wild turkeys). The causes for lasting relevance could be accounted to the presence of more native Americans than pilgrims in attendance, and the hope that the abundance of the harvest, and other naturally occurring food resources, instilled in them for their future success (and therefore, ours) in this new land of liberty.
You may read the letter written by the Mayflower pilgrim Edward Winlsow in which he describes that three-day feast, with modernized spellings: here. If you would like to read it in its original, it can be found somewhere in this book: here. It’s only a few pages and may spark your interest to read something larger, like William Bradford’s whole account of the pilgrims’ journey and establishment at the Colony of Plymouth (Plimoth Plantation); which you may read for free: here. Or, for just a few seconds of your time you could also read the original Mayflower Compact.
The following is an excerpt from William Bradford’s journal:
I may not here omit how, notwithstand[ing] all their great pains and industry, and the great hopes of a large crop, the Lord seemed to blast, and take away the same, and to threaten further and more sore famine unto them. By a great drought which continued from the third week in May, till about the middle of July, without any rain and with great heat for the most part, insomuch as the corn began to wither away though it was set with fish, the moisture whereof helped it much. Yet at length it began to languish sore, and some of the drier grounds were parched like withered hay, part whereof was never recovered. Upon which they set apart a solemn day of humiliation, to seek the Lord by humble and fervent prayer, in this great distress. And He was pleased to give them a gracious and speedy answer, both to their own and the Indians’ admiration that lived amongst them. For all the morning, and greatest part of the day, it was clear weather and very hot, and not a cloud or any sign of rain to be seen; yet toward evening it began to overcast, and shortly after to rain with such sweet and gentle showers as gave them cause of rejoicing and blessing God. It came without either wind or thunder or any violence, and by degrees in that abundance as that the earth was thoroughly wet and soaked and therewith. Which did so apparently revive and quicken the decayed corn and other fruits, as was wonderful to see, and made the Indians astonished to behold. And afterwards the Lord sent them such seasonable showers, with interchange of fair warm weather as, through His blessing, caused a fruitful and liberal harvest, to their no small comfort and rejoicing. For which mercy, in time convenient, they also set apart a day of thanksgiving. . . .*
Other websites which are particularly plentiful in all things pilgrim include the following: http://www.histarch.illinois.edu/plymouth/index.html http://mayflowerhistory.com/ http://www.pilgrimhallmuseum.org/ https://www.plimoth.org/learn/just-kids http://www.plimoth.org/learn/multimedia-reference-library/read-articles-and-writings/thanksgiving-history https://www.gilderlehrman.org/history-by-era/early-settlements/resources/pilgrims-mayflower-compact-and-thanksgiving *The source for Bradford's journal entry is: http://www.whatsoproudlywehail.org/curriculum/the-american-calendar/excerpts-from-of-plymouth-plantation#return8