The AHS Daylily Journal had a really good article last year on eating daylilies and it had some recipes, but that is all I remember right now.
I have tasted a few of my daylilies and the lighter colored daylilies taste like lettuce to me. The reds have a more bitter taste. I don't remember most of the ones I tried, but I do remember trying Yellow Ducky and it was good! I usually only eat one or two petals, so have not had any issues with stomach troubles.