My T accepts cards gladly. She will accept small gifts, but always says that it wasn't necessary, etc., though not in a way that makes me feel bad and it's clear that she is appreciative. I tend to get her something around the holidays from my annual trip abroad. I make it something significant to us/our relationship. And she has gotten me a few gifts - again small and personalized. I also got her a small potted plant when she moved into a new office. The first Christmas we worked together I didn't ask ahead of time and got her some dark chocolates from Europe - cost probably $7, just a token something (we'd both talked about our love of dark chocolate). She accepted them and said it wasn't necessary. But in retrospect it might have been a good idea to check it out first.