Simplify the following text for a Grade 11 native English-speaking person.
Original: Edda or the plural Eddas or Eddur , including Poetic Edda ( or Older Edda ) and Prose Edda ( or Younger Edda ) , are two collections of stories about Viking deities .
Simplified: The Poetic Edda , also known as SÃ mundar Edda or the Elder Edda , is a collection of Old Norse poems from the Icelandic medieval manuscript Codex Regius ( `` Royal Book '' ) . Along with the Prose Edda , the Poetic Edda is the most expansive source on Norse mythology .