There are like a million varieties of clover. (OK, 300). Does anyone know of any Native North American Clover that likes swamps and has a particularly interesting flower?

There is a section of lawn that is swamp all Spring, but dries and is mowed in summer. I'm looking for something that would be visually interesting and/or a bee and butterfly attractant during the months it can't be mowed anyway. Clover can be mowed, so the right variety might be an option.

Also interested in decorative grasses or wildflowers that can survive spring swamp and summer mowing.