Discovery of the Runes/Creation of the Runespells

Odin, seeking knowledge, desired the wisdom of the Norns. These terrifying women carved symbols into the trunk of Yggdrasil, the Great World Tree. The power of these symbols then spread throughout the Nine Worlds, influencing the fate of all of reality.
The god learned that knowledge of these Runes came from the Well of Urðr, nestled among the roots of Yggdrasl. Upon learning that the knowledge would only come to him with great sacrifice, Odin drove his own spear into his side and hung himself, upside down, among the branches of the World Tree. For nine days and nine nights, Odin stared into the depths of the Well of Urd until, at last, the Runes appeared, floating up through the waters of the Well.
With the appearance of the Runes came the knowledge of what they do and how to use them, for the Runes are more than just an alphabet. Each Rune has a spell-like ability that can be used if one knows how. For Odin, this ability is now a part of who he is.
However, Odin did not keep his new knowledge a secret. He share the Runes freely, particularly on Midgard, proving his power. And the Norns carved the consequence of his actions into the trunk of Yggdrasl.
The Runes manifested into the world of Midgard as physical pendants, appearing to be made of silver, though they were never crafted. These Runespells created a balance between gods and mankind by allowing mortals the ability to use the power of the Runes when holding the appropriate Runespell.

In Literature

Hávamál: The Words of Odin the High One by the Elder or Poetic Edda (Sæmund's Edda)
The Prose Edda by Snorri Sturluson

In Art

Date of First Recording

800 to 1400 CE.
The oldest surviving text is as part of the Poetic Eddas, in the Hávamál, written in 1270 CE by Snorri, a Christian monk

Date of Setting

Unknown