The Pearl: A Middle English Poem; A Modern Version in the Metre of the Original. I think I'd have preferred if they left it in the original Middle English, but online period sources are always useful.
A Short Biographical Dictionary of English Literature. Mostly post-period, but really pretty good coverage. Includes authors dating back to Saxon times, so their definition of "English" has more to do with the island than the language.
A Short History of Monks and Monasteries. Self-explanatory title; content is mostly SCA period.
Characters and Events of Roman History, from Caesar to Nero. Actually a collection of turn of the century lectures from the Chatauqua Institute (where I spent many summers growing up). Some interesting-sounding topics, on both the people and the society.
Library of the World's Best Literature, Ancient and Modern, v.4. This volume includes (among others) Alexander Barclay, various snippets from Beaumont and Fletcher, some letters of Beethoven, Jeremy Bentham (hey, I just did a course on philosophy, so I actually care). Bishop Berkeley, Bernard of Clairvaux, Bernard of Cluny, Juliana Berners' "The Treatyse of Fysshynge with an Angle", some translated excerpts from the Bestiary of Guillaume Le Clerc, and the ancient author Bion.
A General History of Voyages and Travels, v. VI and v. VII. Mostly sixteenth-century this time, including Cabot's discovery of Newfoundland.
The Common People of Ancient Rome. Mostly about Latin, its poetry and literature, as far as I can tell.
A Book of Fruits and Flowers (1653). I actually have this one in hardcover facsimile. Very useful just-post-period cookbook, with all sorts of recipes for preserves and candies and such.
Hindu Literature: comprising The Book of Good Counsels, Nala and Damayanti, The Ramayana and Sakoontala. Mostly before SCA period, actually.
The Certainty of a Future Life in Mars. One of those distinctive curiosities from the beginning of the 20th centuries, occupying the fuzzy middle ground between science fiction and spiritualism. Supposedly a posthumous true account: take that as you will.