(I've seen them flying overhead a few other times in the past, but not normally this LOW! The current cloud ceiling is apparently 4200 feet, so I don't know why they'd be flying that low over a residential area.)
I didn't get a good enough look through the tree out back to tell exactly what kind it was & what markings it had (though it was certainly low enough, had I been faster at getting to the window and finding the right direction to look), but I think it might have been an AH-1W Super Cobra (though dark green rather than grey like that one).
Whatever it was, it had one heck of a large gun slung under the nose. And it looked like the gun was pointed down rather than up!
ETA: And now a second one (or the first one again, though it looked grey this time) went over the front yard. A little higher this time, but still only a few hundred feet. I didn't have a good enough angle this time to see the sides, but I'm more confident that this one was probably an AH-1W.
ETA2: Must be some sort of maneuvers going on. A formation of three Chinooks (or something similar with two main rotors) just flew over from northeast to southwest. (Whereas the previous two 'copters were both flying due west.)
ETA3: And now what looks like a MH-53M Pavelow just flew by at around 200 feet, following the exact same path as the first helicopter; which, now that I look at it, might also have been a Pavelow, though the second was definitely a Super Cobra.
ETA4: And the Super Cobra just flew back the other direction, so maybe the exercise is over.
Feudalism: Serf & Turf