A couple of things to consider
1. the leaf litter the plants deposit in your pond.
2. Shading of the pond that reduces water lily growth. Plants on the north side won't shade.
We have damp soil around our ponds. I like pond cypress, elderberry, and sweetbay magnolia.
These will grow in mississippi. But will they have the same properties?
The pond cypress will get huge in a 1,000 years or so. They are relatively slow growing and one or two planted ten feet from the pond won't drop many needles in the pond.
They don't get much spread and grow sort of pyramidal.
The elderberry blooms a lot with white clusters of flowers. Birds love the Barry's, if you don't you can clip them off before they ripen. When the elderberry is happy it will thicket and make a nice grouping of plants with lacy foliage.
Sweet bay magnolia is an evergreen in the south. It generally stays a small tree.
In Florida the elderberry and sweet bay are evergreen. You might check to see if they are evergreen at you latitude.
Have fun,
Al