Carolina mosquito fern, Azollacaroliniana Willd., is a small floating aquatic plant that is native to this area. It can often be found with duckweed . Both are suitable for water features. I have a small population growing in decorative ceramic containers. I even entered one in the County Fair in the small fern category, but the judges defined potted plant as soil borne only thus no aquatic plants were considered despite mine by far being the smallest since it was in a container little bigger than a thimble. There is also an exotic species, Azollapinnata R. Br., known as feathered mosquito fern that is considered to be a noxious weed. As far as I know it is only reported from North Carolina.