Thank you present?

Sydney
I want to get my boss a small thank you present because I've had to take a lot of days off for school lately. I can tell she's a little frustrated. I want to stay on her good side so I wanted to get her a small thank you present. 
I just want opinions on what you think is better!
My first thought was to get a thank you card with a small $15 gift card. (Maybe to start bucks?)
Or my second thought is to make cookies with a thank you card. What do you think is better?