Did the mushrooms get any larger? Any developmental changes would be helpful, too.

I really don't know... I don't think birds or other animals eat them. Maybe water dispersal? But I'm from the roughly the same area as you, and I see them around here. I have also seen those mottled purple leaves. I think that the question, how are morning glories dispersed? would be a good one (to ask seperately) for this SE.

It's still kind of hard to be sure but I think it's buckthorn. I edited my answer to include pictures showing what to look for. What you want to look at, is how the berries are connected. Are they in bunches or are they individually connected at the base of the leaves? Also, are the leaves serrated (like a saw) or smooth on the edges?

Yep, and to add a name, I'm pretty sure it's the yellow parasol mushroom, which can cause ulcers of the stomach (if eaten).