Since I never actually got around to posting it earlier, here's the dumps I'm aware of in my area...
NS:
Huntsville, AL:
https://www.google.com/maps/@34.7350253 ... 312!8i6656
This one has since been redone (the yard office across the crossing was moved over next to it) and is now entirely enclosed.
Scottsboro, AL:
https://www.google.com/maps/@34.6746494 ... 312!8i6656
Not much too it, but the signals that are now at Market Street (just east of the crossing) were stored here before being installed.
Attalla, AL:
https://www.google.com/maps/@34.0177826 ... e3!5m1!1e4
No street view, but NS does have a small signal dump over by the diamonds there.
CSX:
Decatur, AL:
https://www.google.com/maps/@34.5931721 ... 312!8i6656
That signal dump is located within Oakworth Yard, but the manager in charge of it is pretty nice. He also likes old signals & equipment, so he has a bunch of older block signals on display with various safety slogans around the building.
The emergency knock-down replacement signal there is also used as a gate for getting in/out of the building (can be seen to the left of it) and has a WCH mechanical bell on it as well.
Ardmore, AL:
https://www.google.com/maps/@34.9910364 ... 312!8i6656
Like Scottsboro, there ain't much too it, but there is a small one right behind that little yard office. Sadly, the equipment in it can't really be seen on street view.
Shortlines/other railroads:
Gadsden, AL:
https://www.google.com/maps/@34.0183835 ... 312!8i6656
The ATN keeps most of their old signal equipment right at their offices in Gadsden. However, some of it's also kept over here by the NS Siskin Yard:
https://www.google.com/maps/place/34%C2 ... 17!5m1!1e4
Red Bay, AL:
https://www.google.com/maps/@34.4422833 ... e3!5m1!1e4
The Mississippi Central has a signal dump by their offices in Red Bay. Again, no street view here.
Lebanon, TN:
https://www.google.com/maps/@36.197082, ... 92!5m1!1e4
The NERR also has a dump right by their offices. The building seen (across the driveway from the shops, which you'll see if you pan to the left) has a massive pile of 3rd Generation Modern Industries 12 inch lights behind it.
Anyways, that's all of the signal yards I can recall off the top of my head.