Several stories about Goddess Kamakhya Devi are mentioned in many ancient Scriptures including Puranas. Kalika Purana is the best source to get information about the Goddess of Fertility..
Vatsayana, a Vedic Sage in Varanasi during the later first Century was approached by the King in the Himalayan region (now Nepal) to find a solution to convert the tribals and their rituals of human sacrifice to a more socially accepted worship. The Sage suggested the worship of a tantric goddess Tara that spread towards the eastern Himalayan belt till the Garo Hills where the tribals worshipped a fertility ‘yoni’ goddess ‘Kameke’.
It was much later in the later Brahaminical period Kalika Purana that most tantric goddess were related to the legend of ‘Shakti’ and began to be erroneously worshipped as a ‘devi’ by the Hindus.
According to the Kalika Purana, Kamakhya Temple denotes the spot where Sati used to retire in secret to satisfy her amour with Shiva, and it was also the place where her yoni fell after Shiva danced with the corpse of Sati.
This is not corroborated in the Devi Bhagavata, which lists 108 places associated with Sati’s body, though Kamakhya finds a mention in a supplementary list.
The Yogini Tantra, a latter work, ignores the origin of Kamakhya given in Kalika Purana and associates Kamakhya with the goddess Kali and emphasizes the creative symbolism of the yoni.