Moldavite-looking rock from ND USA?

So, I just got a rock tumbler and it made me go through all the cool rocks I had.

I remember finding this green translucent piece. Glass-like, matte, and wrinkly, like Moldavite, which someone suggested it could be when I posted it here awhile ago. It was pretty big, like almost as large as my palm

Unfortunately, I just cannot find the picture I had, and EVEN worse, I can't find the rock.

Does anyone know what the rock could have been? I mean, it was in the mud of a North Dakotan river, and from what I understand, Moldavite cannot be found in the U.S. naturally(?)

I'm just wondering how sad I should be.