Q. I was embarrassed because my boss gave everyone in the department a holiday gift and some of the people gave her presents, some of us did not. Are we supposed to run out and buy her something now, after the fact? Or do we just ignore it.
Ans. Don't do either. Your boss didn't buy you a present in order to get one back.
Write a very nice thank you note, something a lot of people overlook these days. Include a comment about how much you enjoy working for her, and say you look forward to another productive year working together. That should mean more than a gift from you.