This is the first official day of spring on the Pagan Wheel of the Year, the time when animals start their mating season-- especially sheep, which were very important to the ancient Celts. The traditional Goddess for this Sabbat is Eostore, the Anglo Goddess of rebirth, fertility, dawn, and new beginnings. This holiday falls around the same time as Easter and it is traditional to eat lamb on Easter in many places, as with Ostara.
Wiccan rituals may include blessing seeds to plant later. On the Vernal (Spring) Equinox, day and night are perfectly balanced. The Goddess and God are in perfect accord and fall in love, ensuring that the world will regenerate during spring.
the above is taken from Where to Park Your Broomstick by Lauren Manoy p.205-6.