If it is far enough away from the house Salix.

I agree with MG about salix (willow). Also, some irises prefer very wet ground as well as plants such as marsh marigold or bulrushes. Have you thought about the possibility of putting in a small pond and making the most of the fact the water collects there naturally?

Salix is a good idea, but only if the area concerned is over 40 feet away from your house.