Governor William Bradford's own history, Of Plymouth Plantation, is the ultimate primary source for Plymouth Colony. This edition, edited by me, also includes the Pilgrims' journals for their first year at Plymouth, often nicknamed "Mourt's Relation." My edition also includes a number of images and documents. I strongly encourage you to get the hardcover version: at 620+ pages the softcover does not hold up all that well, and this will be a book you refer to frequently if you have any interest in the Pilgrims. If you like the cover artwork by Mike Haywood, it is available as a giclee print on the Paintings and Prints page.
PLEASE BE FOREWARNED. The text of these primary source books are all available in full, for free, on my website, on the Primary Sources page. I am including these in the bookstore for those who want to read and study them in book form rather than trying to read or study something online. In some cases it is almost cheaper to buy these very inexpensive books than waste paper and ink printing out something from the Internet. Also, "Mourt's Relation" is included, in full, in my Of Plymouth Plantation edition above, so you would not need to purchase it separately.