Thanks for the info on Calendula. To tell you the truth, I had only ever been exposed to the one type of Marigold(common/french). I had no idea there were so many other kinds.
I'm going to have to look into this more to find out if they would all taste different, if any are not edible, and if they have different effects on the soil, plants, and insects around them. I think the Marsh Marigold is really pretty.