Veneralia, the feast of Venus, although the masses use the modern name Easter with celebrations that include chocolate bunnies and church.
As you know, I tend to like to delve deeper and look at source material, like where exactly did this ritual come from? After all, Spring existed here on planet Earth long before the arrival of the individual named Jesus.
April by the Romans was considered the month of Venus, just after March, attributed to the war God Mars. In Greece the name for Venus, the Goddess of Love and Fertility, was Aphrodite (Aphro meaning seafoam, and dite, bright.) Journeying further back we have Astarte from Phoenicia, a deity that may have been worshipped as far back as 1000BC and the potential source material for Venus, Aphrodite and imagery associated with Mary. 1
We already know that the Goddess culture existed long before the patriarchal Gods took over sacred sites where names were changed or great cathedrals built. It's possible that with the melting polar caps, particularly in Antartica, more clues into ancient time will likely be revealed shortly.
Opening image: The Birth of Venus by Alexandre Cabanel via wikipedia