Looks like A. Caesarea but since the volva is lacking it might be A. parcivolvat and it is a common eastern species. The fact that you found it near ariver bank makes me think that also. I have seen This same fungi growing near the river bank on the New River in West Virginia.

The white is stipe interior where it was broken, not a saclike volva.
I dug around the base and did not see any evidence of a volva.

No striations on the cap margin, also no yellow gills, I do not think this is in the caesarea group.

Is that a sac like volva in the 3rd pic? Its hard to tell if that is the base were you broke/cut it or a volva.