Starfall

The myths of Poneren suggest the gods created humanity, bringing them from the mountains to the lower land below.
As part of this myth, it is believed that humanity was created from the stars. Every year in late winter there is a three-day period of nightly meteor showers, a rememberance (it is said) of the time of creation, of the place of humanity on the world.
Occurring shortly before early spring, Starfall is a celebration of creation and rebirth. Houses are cleaned to prepare for spring, and presents are given to celebrate the start of a new year.
The celbration stretches over three days and two nights, with most of the activities occurring after the sun has gone down and the stars are out. In good years, the falling stars are visible, and even in the bitter cold people will stand outside around bonfires celebrating, or sneaking off into the dark to just stare at the skies above.
On the first night, presents are given by elder people to younger ones: parents to their children, teachers to students, older siblings to younger, or even husband to wife. This is a reminder of the gift of life, and how none could have done anything on their own.
The second night, then, has the younger gifting to the older. This is a reminder of thankfulness and how the gifts recieved should be gifts shared.
It's also often found that this is practical -- the younger of a pair tends to be the more likely to forget or be unable to get a gift on their own, and often may use the first day as a reminder or a means of getting help in getting a gift they would like to give.

History

The tradition started early in Poneren history, as a rememberance of the past and arrival on the planet. With a few harsh winters and difficult times, the festival quickly fell away and was lost for most of a generation while humanity attempted to solidify a toe-hold on the planet.
By the time the future was safe, the past was mostly forgotten. As magic began filling people's hearts, all that remained of the early tradition was the memory of a beginning.