The holiday was celebrated with a sacrifice at the Temple of Saturn, in the Roman Forum, and a public banquet, followed by private gift-giving, continual partying, and a carnival atmosphere that overturned Roman social norms: gambling was permitted, and masters provided table service for their slaves as it was seen as a time of liberty for both slaves and freedmen alike.
Is this where elves come from?
https://en.wikipedia.org/wiki/Saturnalia
No, elves come from Norse mythology
Xmas is a mishmash of Saturnalia and Yule with a landlord special coat of Jeebus on top.