The Gospel of Thomas is a sayings collection of 114 logia attributed to Jesus, discovered in 1945 at Nag Hammadi (Coptic, Codex II) with earlier Greek fragments from Oxyrhynchus dating to the early 3rd century. Scholarly consensus dates composition to approximately 50-120 CE, making it potentially contemporary with or earlier than some canonical gospels.
Standard editions: Robinson (ed.), The Nag Hammadi Library in English (Brill, 1977/1996); Layton, The Gnostic Scriptures (Doubleday, 1987)