There is a Bibliography section in the project that could be used for a start.
The Greater Society of Mayflower Descendants is publishing a series of books called "Mayflower Families through Five Generations." These books, often refered to as the "Silver Books", are sold by online booksellers and online at AmericanAncestors.org. Some local public libraries have these books.
The Great Migration Begins series, published and sold by NEHGS, contain biographies of each Mayflower Passenger and their known children. Often primary source documents are cited as references. There is a subset of the Great Migration Series has been published recently. titled "The Pilgrim Migration". It covers the immigrants to Plymouth Colony and their wives and children.
Saints and Strangers by George Willison has some background material about the Pilgrims' time in Holland, the perilous adventure and the first years of the settlement.
Bradford's History is recommended reading. I believe that it can be read on line.
Bangs, Jeremy Dupertus, Strangers and Pilgrims, Travellers and Sojourners - Leiden and the Foundations of Plymouth Plantation, General Society of Mayflower Descendants, Plymouth, Massachusetts, 2009 Details from the Leiden, Netherlands archive records for those who came to Plymouth Colony.