If I, in a thick Appalachian accent, referred to a location as “a holler,” would you know that it meant “hollow,” as in “valley”?
It sounds more like “HAW-ler” to me. I don’t hear an “i” before the “e”. That I would know was a valley.
I knew about holler/hollow from reading and a bit of personal experience during the years I lived on the east coast. Since I moved to Chillicothe, with its Appalachian population and a countryside replete with named hollows, it’s a part of normal conversation. But you used to live in these hills, jsgoddess, so you know. 
Yes I would. My grandparents are from West Virginia and I’ve heard my grandfather in particular use holler as a synonym for valley many times.
Yes. So is Loretta Lynn. 
Ha…I have heard the term many times (as you know, Ohio is pretty much West West Virginia, even up here in the city) but I just knew that a holler was a valley, and not that it was a “mis-pronunciation” of “hollow.”
Yes, and I call the low spot between two large hills in a wooded area a holler to this day.
Although I lived in east Tennessee for a while, it would surprise me if the general public was unaware of that pronunciation. I mean, there have been enough movies and TV shows that I would expect everyone to have been exposed to that pronunciation.
I’d expect more people to not know that “hollow” (or, holler if you want to be in-dialect) meant “small valley” than not know that when someone speaking with an east Tennessee (or, Appalachian) accent says"I just about turnt my ankle when I fell over that holler log sittin’ at the bottom of Rattlesnake Holler" they mean “I almost twisted my ankle when I fell over that hollow log that is at the bottom of Rattlesnake Hollow”.
Indeed. And for examples, don’t overlook the country classic, “Deeper Than the Holler” from Randy Travis.
For me, the OP immediately called to mind various country music songs that use the term holler - especially the Randy Travis one cited above.
Of course. And yeller is the color of your dog. The air comes in through the winder, if you got it open. You sleep with your head on a pillar, which is more comfortable than it may sound. And if your kid teases you about your accent, you’re gonna swat beforementioned kid on the sitting-parts with a willer branch.
ETA: my relevant relatives were not uneducated and knew that these words were spelled “xxxxow”, which led to a letter from my aunt to my dad in which she stated that her sick crying son was currently in his room, “hollowing out the window” for all he was worth.
I have cousins in the Kentucky hills.
My Tennessee grandparents said holler, winder (window), yeller, and unrelated but along the same line said “rench” for 'rinse", as in “rench yer hair under the spicket”.
Snuffy Smith lives in Hootin’ Holler.
Absolutely. My dad grew up in one (eastern KY). His family relocated to OH where he met and married my mom, and that’s where I grew up. I don’t have the accent, but it sounds like home to me.
Now the revenue man wanted grandaddy bad,
he headed up the holler with everything he had.
It’s before my time but I’ve been told,
he never came back from Copperhead road.
Conversely, my SO from the Virginia hills still drops in “rinse” for “wrench” on occasion.
No, you do not. You sleep with your hay-id on a piller! 
Oh, and sorry OP. For some reason I saw an extra “i” in your spelling of holler. Had the wrong glasses on this morning. I’ll fix that tomorrer.
Ah. Thursdee.
Great song.