How about leucistic grackle (either a Common or Boat-tailed)? Here is a photo of a leucistic Boat-tailed: https://thumbs.dreamstime.com/b/leucistic-boat-tailed-grackle-quiscalus-major-white-head-green-background-55479517.jpg
Have you looked at photos of Green Herons (young and adult) on Google or Macaulay Library? They can hold themselves in all sorts of positions and some have bright yellow legs. Your description of plumage still fits Green Heron well.
Eastern Phoebe (brown color above, completely black beak, no eyering). It appears to be a juvenile due to the visible gape flange and the cinnamon wingbars.
I'm thinking this is a fledgling Red-winged Blackbird that hasn't grown feathers on its face yet. Like this: https://www.flickr.com/photos/feltonphoto/7324816742