What to buy as a gift for your girlfriend who is on her period?

My girlfriend gets a little nervous and aggressive during her period. I know this is normal and I try to be more submissive. But sometimes being submissive is not enough. Things like chocolate or sweets make girls happy but they are forbidden because she is on a diet. So I want to buy her a gift other than food to make her happy. What gift can I buy her that won't be too expensive?

What to buy as a gift for your girlfriend who is on her period?
Post Opinion