Reddit reviews Eleusis: Archetypal Image of Mother and Daughter

Some resources:

Eleusis by Karl Kerenyi - focusing on the Mysteries of Demeter and Persephone

Queen of the Sacred Way devotional anthology - essays, poetry, etc by modern worshippers (I have a poem in there)

Bakcheion page on Persephone with several poems, links, resources, essays - this is a Dionysian group but they also include many other deities

I posted this a few days ago; just ignore the Norse stuff. As far as non-fiction, you can't do much better than the work of Walter Burkert. Ancient Greek Religion is probably a better introduction; you'll have to read something about Eleusis, too.

If you'd like to get into myth in general, definitely look into archetypal theory and criticism. It can be challenging, but it's very much worth it and quite illuminating.

EDIT: It might also be a good idea to keep this on hand.