Yes, you should still send them a thank you card. It’s understandable that you may be a bit disappointed that you didn’t receive a gift, but what matters more than a present is that they made it a point to travel and attend your wedding. Simply thank them for being with you on your special day. Keep your messaging gracious and heartfelt. Speak to a moment you shared with them at the wedding or how much it meant to you that you were able to celebrate with them in attendance. And you never know, there is always a possibility they simply forgot to get your gift in the chaos involved in planning to attend. Your thank you gesture may remind them they still need to send a wedding gift.