The Coffin Texts
When
c. 2100-1800 BCE, First Intermediate Period and Middle Kingdom
Where it survives
Painted inside wooden coffins, chiefly at Asyut and Deir el-Bersha
What it is
The successor to the Pyramid Texts, now available to officials rather than kings alone. Includes the Book of Two Ways, the earliest known map of the underworld.
Read it with this in mind
The spread beyond royalty is the single most important development here, and it is easy to miss because the spells themselves look similar.
Myths attested here
Creation at Heliopolis
c. 2400 BCE, in the Pyramid Texts
One god alone on a mound in the water, producing the first pair from himself.
The eight of Hermopolis
Middle Kingdom onward, elaborated in the Graeco-Roman period
Four frog-headed gods and four snake-headed goddesses, standing for the qualities of the water before there was anything.
Other sources