Marsh Marigolds are common here wild in most any marshy area (spring blooming), they can be located at most nurseries carrying pond plants, however the picture you have seems to have a double flower, more common is the single which looks more like a buttercup. As for the other it looks a lot like a Christmas Cactus, but by the name I think maybe an Orchid of some type, I would think it would be tropical, and if a cati not wanting to have wet feet in a pond. Maybe Joyce will give you a better answer.