If you're looking for a relaxing tea, I highly recommend lavender. I use a tea ball filled with dried flowers that I bought in bulk online. Honey optional. Chamomile is nice, but it has never done much for me beyond "a cup of something warm is relaxing".

I also find that lavender oil works really nicely in an oil diffuser, but it turns out that my husband is terribly allergic to it, so I don't use it that way anymore.