In addition to things of immediate material value, I'd have to add some timeless classics of literature and leadership -
The Anabasis Xenophon (Aka "The Persian Expedition")
An abridged version of The Peloponnesisan War Thucydides
Aesop's Fables
Beowulf
The Song of Roland (There are particular translations of both Beowulf and Roland that are much more readable than others, the translators' names elude me but the best Roland is one of the Penguin editions with a female translator, while my favorite Beowulf was done in modern English by a male writer)
Sir Gawain and the Green Knight Tolkien translation
An Arthurian compendium of some sort, though the translation of Le Mort d'Arthur I have is a bit too laborious reading for my taste, perhaps something like Tennyson's Idylls of the King
Robin Hood
The Tales of a Thousand Nights and a Night, Burton translation
The War of the Worlds
I'll go along with Big Dog on Sun Tzu and MacBeth
Poetry collections of Rudyard Kipling and Robert Service
Attacks by Rommel (A timeless classic of military and crisis leadership, which like Sun Tzu teaches a method of thought and approach to crises to the astute reader, rather than simply recounting dated gambits and stratagems)
The Battle of Duffer's Drift (For similar reasons as Attacks)
The Swiss Family Robinson
Sherlock Holmes collection
Mark Twain collection
There're probably some more Interwar and Post-war items I would include but none of them spring to mind, and off-hand I can't think of anything written in the last few decades that compares to any on the list above.