In Hebrew, ‘Eden’ means delight. The Garden of Eden was the first home of mankind, according to the book of Genesis in the Bible. It is described as a paradise on Earth, home to Adam and Eve, the first humans created by God.
East of Eden lies the Land of Nod, to which Cain was exiled after killing his brother Abel. 'Nod' means wandering. John Steinbeck's novel, East of Eden, concerns a brother's betrayal. Neil Gaiman was working on his first Sandman graphic novel at the same time as Good Omens; it features Cain and Abel and references the Land of Nod.