CROTON, Codiaeum variegatum. Many, many cultivars. Joe

It sounds like your bright orange chested "sparrows" are orioles--either Bullock's, or maybe Hooded. You are in California, aren't you? Do you have a good pair of binoculars? If not, buy or borrow a pair and maybe you can get a better view of your mystery hummer. It should be easy to tell a male Anna's from a male Rufous, as long as the light is good and you can get a decent view of "Mr. Bashful." If you can't see the back, pay attention to whatever you can see, like the belly and sides. Are they distinctly rusty in color? If they are, that narrows it down to an Allen's or a Rufous, and rules out the Anna's. The belly and sides of an Anna's are more grayish greenish. The males of both Allen's and Rufous (and Anna's too!) have glittering red throats. Because the red is iridescent, the red could take on a little different shade depending on the lighting and your viewing angle. Don't let that confuse you. The most obvious difference between those two species is that the Allen's has a glittering green back (that may look dark in certain light) and the Rufous has an entirely rusty back, the rusty sometimes intermixed with glittering green. As for the Anna's, it's the only one of the three that has glittering red on the top of the head, (as well as on the throat) and that may extend a bit down the upper back--but not half way, unless you've got an unusual individual. So, when you catch a glimpse of him again, get your binoculars, and try to see if he has any rusty non-iridescent red on his belly or on his back. Pay attention to the back and try to get the colors. Is it glittering green, or is it rust colored? Is the top of the head glittering red (Anna's) or green (Rufous or Allen's)? These features should help you tell the males apart of these three species. If you can get those binoculars, you might also get a better look by stationing yourself outside, at a respectful distance from the feeder, with the binoculars to your face and trained on the feeder. Then, if you stay very still and are excruciatingly patient, he might show up to feed. If he's really shy, just lifting the binoculars to your face might scare him. That might be the only way you'll get a decent look at him. Here is a link that might be useful: Picture of a Bullock's Oriole

I suspect the only reason I do not have more buckwheat is because I tilled the garden vigorously before planting. If it goes to seed, it is right at the edge of the box so will likely spill out into the yard. Cilantro did the same last year and now I have cilantro without any effort while also not taking up any garden space. Win/win for everyone. Such flowering plants may be why I have had great returns with zucchini pollination---I get the sense from reading that squash returns vary greatly without pollinators. If the same holds true for winter squash, I will be making lots of butternut stew.

It’s ID’ed here on Houzz as Typhoon Bordeaux Granite. Pics in other kitchens: https://www.houzz.com/photos/query/typhoon-bordeaux-granite