Whatbird.com

I should point out that since you saw two different white-throated sparrows on this day, this one looks to be of the tan-striped variety.  The other white-throated sparrow you saw is of the white-striped variety.  They are the same species, and have the same pattern, but one has tan stripes on the head where the other has white stripes ...

This one is also a song sparrow.

This one is a song sparrow.

White throated sparrow.

White throated sparrow, I believe.

Hermit thrush is correct.

Yes, orange-crowned.

I agree.

To be standing in an open field or marsh and have a flock of hundreds of thousands of blackbirds go over my head, hearing the whoosh of their wings as they pass by, is one of my favorite moments in birding and in being in nature in general.

If it was that big, dark bluish gray, and with a crest, it could've been a Cooper's hawk, which at times can appear to have something of a crest.  I could see how if you only saw certain parts of the bird, it could look quite jay-like in pattern.  If you got a good look at the head and bill though, I don't imagine that could be construed ...