For the winter solstice, Druids in ancient Britain would gather a forest plant that we now associate with Christmas.  It was:

In the time of the Druids, mistletoe was believed to have magical properties.  People who met under a tree bearing mistletoe were forbidden to fight, even if they were enemies, and anyone who entered a home decorated with mistletoe was entitled to shelter and protection.  Mistletoe may even have been part of Druidic wedding ceremonies.