Parillia was a festival in honor of Pales, the god of shepherds. Their was offerings of milk, grain and cakes to the God and it was a festival of protection & fertility. It encompasses both rural and urban celebrations and parts of other rituals.Blessings,
It originated as a purifying festival, but later was considered the birthday of Rome starting in 753 BCE. The beginnings of this festival are unclear. It is thought to predate the founding of Rome and stem from the early pagan celebrations.
The is some speculation surrounding Pales as well. We don't know if Pales was male or female, whether or not this festival was actually ascribed to Pales as well.
Sources:
http://www.pagancalandar.co.uk
http://en.wikipedia.org/wiki/Parilia
Petra