Fertility

One of the oldest forms of fertility symbolism was the use of the serpent. The snake was commonly associated with the umbilical cord, joining all humans to the Mother goddess. Many ancient civilizations depicted the Mother goddess as having snakes. Serpents were often worshiped as guardians of Her sacred mysteries of birth and regeneration.

Hopi people
The Hopi people of North America performed an annual snake dance to celebrate the union of Snake Youth (a Sky spirit) and Snake Girl (an Underworld spirit) and to renew fertility of Nature. During the dance, live snakes were handled and at the end of the dance the snakes were released into the fields to guarantee good crops. "The snake dance is a prayer to the spirits of the clouds, the thunder and the lightning, that the rain may fall on the growing crops."