The Bay Psalm Book
Only 11 copies of the 1640 edition of the Bay Psalm Book are known to exist and only five of those are complete. Two were owned by Old South Church in Boston until it sold one of them in November, 2013, for $14.2 million.
The complete copy in the John Carter Brown Library at Brown University can be viewed online on the World Digital Library website.
The copy of the Bay Psalm Book owned by the Library of Congress is on the LOC website.