Let me just say first off I love my therapist she is amazing and helped me with so much but I would not get her a gift unless it was a last goodbye thanks for all your help type of thing and it'd probably be a thank you card, now I have issues with getting close to people so maybe it's easier for me to look at our relationship objectively but I do not feel it is appropriate to give her a bday gift maybe a greeting by saying Happy Birthday if I saw her around her birthday but she is the same as any other professional you go to so it isn't rude or weird to NOT get your therapist a gift in my opinion and a simple Happy Birthday by mouth is better than a gift again that is only my opinion.