Gerhard Hauptmann, The Island of the Great Mother (German Edition: Die Insel der grossen Mutter) (1925)

A boatload of women, but no men, are shipwrecked on a tropical island paradise. Together they create a flourishing women's civilization. One by one, by some mysterious property of the island itself, the women begin to become pregnant. Catch: half the children are girls, half boys. What to do with the boys?

A troubling, insightful, and prophetic novel.

Robert Graves, Watch the North Wind Rise (American Edition: Seven Days in New Crete) (1949)

After an American-led West and a Sino-Soviet-led East destroy one another, a flourishing civilization centered around the worship of the Triple Goddess arises worldwide. But there's trouble in paradise: things are too perfect. So the Goddess whistles up Robert Graves from the troubled 20th century to spike the punch.

Favorite line: “The Goddess is merciful to fools.”

Plus a Midsummer's ritual you'll never forget.

Margaret St. Clair, The Sign of the Labrys (1963)

One of the very first science fiction novels to be (openly) authored by a woman, and the very first novel to be influenced by the then-emerging Gardnerian Wicca. Civilization collapses for unspecified reasons and what's left literally moves underground. The witches fight a counterinsurgent guerilla war against a repressive military dictatorship.