Aesop's Fables or the Aesopica is a collection of fables credited to a slave and storyteller believed to have lived in ancient Greece between 620 and 560 BC. Of diverse origins, the stories have descended to modern times through a number of sources. Originally in Greek, they were translated into Latin in the 1st century CE. They were known in period from at least the 10th century on, and were translated into most languages. Seven tales appeared in Isopes Fabules, written in Middle English poetry by John Lydgate towards the start of the 15th century. The first printed version of Aesop's Fables in English was published in 1484 by William Caxton.
Period tales about Arthur and the knights of the round table were plentiful, both in the British isles and on the continent, especially in France. Some important authors were Geoffrey of Monmouth, Chretien de Troyes, and Thomas Mallory (Le Morte d'Arthur).
It was extensively used as a source of stories in the Middle Ages.
A collection of over 20 stories by Geoffrey Chaucer written in Middle English at the end of the 14th century. Many are bawdy and/or humorous.
French "songs of deeds." The Song of Roland, the earliest and best, dates from the late 11th century; the translation by Dorothy Sayers is readily available from Penguin and very good. Other well known chansons de geste include Ogier the Dane and Huon of Bordeaux. A version of the latter by Andre Norton was published as Huon of the Horn.
A collection of novellas by the 14th-century Italian author Giovanni Boccaccio (1313–1375). The book is structured as a frame story containing 100 tales told by a group of seven young women and three young men sheltering in a secluded villa just outside Florence to escape the Black Death, which was afflicting the city.
Mid-16th century Italian fairy tales collected by Giovanni Francesco Starapola.
Gawain and the Green Knight
A late 14th-century Middle English chivalric romance.
An anonymous first-hand account of the first Crusade, extensively plagiarized by 12th century writers.
A collection of stories, with morals attached, intended to be used in sermons; the Latin version dates from about 1300 and the English from about 1400. Its connection with real Roman history is tenuous at best.
The Golden Legend
With the exception of the Bible, this vastly influential collection of legendary lives of the greater saints of the medieval church was the favorite book of the late Middle Ages, translated into every European language. It was compiled around 1260 from various earlier sources by Jacobus de Voragine, bishop of Genoa, Italy, in simple, readable Latin. It was "Englished" by William Caxton in 1483. Caxton's version was modernized by F. S. Ellis in 1900 and published in 7 volumes (see legacy.fordham.edu/halsall/basis/goldenlegend). Other translations are available, including a recent one by William Granger Ryan published by the Princeton University Press and reissued in 2012 in one 788-page volume.
The sacred text of Islam, just as the Bible is for Judaism (the Old Testament) and Christianity (Old and New Testaments).
The Lais of Marie de France
Scholars think these poems were composed in the 1170s. Marie de France was a French poet writing in England at Henry II's court between the late 12th and early 13th centuries.
The Life of Charlemagne
Written by the Monk of St. Gall (aka Notker the Stammerer). It is included in Two Lives of Charlemagne (Penguin). This is a highly anecdotal "life" written in the ninth century, and covering many subjects other than Charlemagne.
A collection of Celtic myth and legend in Welsh, written down in the 13th century, apparently based on much earlier oral traditions.
Ovid's famous work was an important source of Greek and Roman myths beginning in the Middle Ages and continuing through the Renaissance.
The sagas are histories and historical novels, mostly written in Iceland in the thirteenth and fourteenth centuries. They contain many incidents that can be excerpted as stories. Recommended: Njal Saga, Egil Saga, Jomsviking Saga, Gisli Saga, Heimskringla.
Norse poetic eddas
Written down in Iceland during the 13th century in Icelandic, they also contain material from earlier sources, reaching into the Viking age. The books are the main sources of medieval skaldic tradition in Icelandic and Norse mythology.
Orlando Innamorato (1495) by Boiardo and Orlando Furioso (1516) by Ariosto
These are actually a single story, started by one poet and completed by another. They are a Renaissance Italian reworking of the Carolingian cycle, "The stories of Charlemagne and his Paladins". The tale is well supplied with magic rings, enchanted fountains, flying steeds, maidens in distress, valorous knights, both male and female, and wicked enchanters, also both male and female.
Mid-16th century Italian fairy tales collected by Giambattista Basile.
A Renaissance Storybook
Compiled by Morris Bishop, Cornell U. Press, 1971.
Especially the 14th-15th century ballads.
Tain bo Cualney
Celtic myth and legend about the Cattle-Raid of Cooley and associated "fore-matter".
The Travels of Marco Polo
Book of the Marvels of the World (French: Livre des Merveilles du Monde) or Description of the World (Devisement du Monde), in Italian Il Milione (The Million) or Oriente Poliano and in English commonly called The Travels of Marco Polo. A 13th-century travelogue written down by Rustichello da Pisa from stories told by Marco Polo, describing Polo's travels through Asia, Persia, China, and Indonesia between 1276 and 1291, and his experiences at the court of Kublai Khan. There is scholarly disagreement on how historically accurate it is, especially the more fabulous stories, but it was translated within Marco Polo's lifetime into other languages and became widely read.
The material created by the troubadour and trouvère, Meistersinger and Minnesinger, the songs of the Goliards, and most other pre-1600 poetry and song lyrics can all be used.
Russian folk tales
These can be tricky if you are trying for authentic pre-1600 material, but there are appropriate stories out there (look for the stories of the Bogatyr in particular, and don't shy away from Baba Yaga automatically because her story was "mined" for modern role-playing game material).
Shakespeare is a rich mine of readily available poetry, soliloquy, and basic story -- most of which is generally well-received and can reach an audience due to prior acquaintance.
Tales from "cultures in contact"
Particularly the Arab world and New World "tales of wonder".
Tirant Lo Blanc
A romance written by the Valencian knight Joanot Martorell, finished posthumously by his friend Martí Joan de Galba, and published in the city of Valencia in 1490.
The Travels of Sir John Mandeville
"Jehan de Mandeville" is the name claimed by the compiler of a book account of his supposed travels, which probably first appeared in Anglo-Norman French, and first circulated between 1357 and 1371. By aid of translations into many other languages it acquired extraordinary popularity. Despite the extremely unreliable and often fantastical nature of the travels it describes, it was used as a work of reference by Columbus and others.