So I was rooting again around in the garage and found a couple plates I had bought a few years back and never tracked down an ID for. Tentative provenance was Paleocene from Montana.
I found this article recently and was wondering if it could be one of the genera/sp described or one of the other genera mentioned in the discussion section.
Trapa, Trapago, Fortuna, Quereuxia.
STOCKEY, R. A., AND G. W. ROTHWELL. 1997. The aquatic angiosperm Trapago angulata from the Upper Cretaceous (Maastrichtian) St. Mary River Formation of southern Alberta. Int. J. Pl. Sci. 158: 83-94.