Following something Vered wrote I googled for mother goddess and ran across Semiramis, a legendary Assyrian queen-ruler who has the misfortune to owe a lot of her google-juice to the tireless efforts of Jack Chick style Christians, promoting a 19th century anti-Catholic propaganda which holds her responsible for inventing goddess-worship (and thus the Catholic cult of Mary).

Most entertaining seeing the edit wars in Wikipedia, where the Chick-ites keep replacing historical facts (as in, the actual legendary stuff made up about her by Roman historians) with biblical-literalist 19th century info.

The actual historical figure, Shammuramat, sounds like a fascinating and remarkable person, one of those rare queens who managed to exercise real political power in the name of her husband and son.
The legends are also pretty cool:

According to the legend as related by Diodorus, Semiramis was of noble parents, the daughter of the fish-goddess Derketo of Ascalon in Assyria and a mortal. Derketo abandoned her at birth and drowned herself. Doves fed the child until Simmas, the royal shepherd, found and raised her.

The Shepherd finds the Babe Semiramis, by Ernest Wallcousins (1883–1976), from Myths of Babylonia and Assyria by D. MacKenzie (1915)

Derketo and Ascalun are names I ran across in the context of Bêlit from Conan, although I’m not sure if they came from Robert E. Howard or Roy Thomas.