It's a six-cylinder hardtop with automatic transmission, so it spent the first half of its life being not particularly valuable. In recent years, though, any first-generation Mustang has been worth restoring. If this is the original engine (which is unlikely, given how easy and cheap engine swaps have always been with these cars), it's a 200-cubic-inch Thriftpower straight-six rated at 120 gross horsepower. The later HSC 4 engine, base powerplant of the early Taurus, was two-thirds of a Thriftpower 200.
The first Mustang fancier (or serious eBay car-parts seller) who spotted this car here probably hoovered up 500 pounds of interior and trim components (I have done the same thing with a '41 Plymouth in the very same yard). With the booming aftermarket in reproduction parts for early Mustangs, there's not so much unobtainium stuff in a '65, but original bits are easy to sell.
Yes, this car had real wire wheels at some point. I'm guessing that point was the middle 1970s.
There's no serious rust, and we can see evidence of bodywork, sanding, and priming here. My guess is that someone began a restoration many years ago, then the car sat for quite a while, and then it was evicted from a storage yard or garage. The strange thing is that it wasn't snapped up at auction before coming to this place.
In these big self-service yards, I see many, many cars that should be highly prized restoration candidates— e.g., BMW E24 6-Series or big 1960s Detroit family wagons— but those cars just aren't worth the five-figure investments needed for a serious rejuvenation. A solid '65 Mustang hardtop is another story.
Even though it was a glammed-up Falcon at heart, the '65 Mustang proved that Detroit could make big profits selling a cheap commuter car with an adventurous image. Passing Corvettes at Sebring (with an automatic, of course), riding the range with cowboys, and catching the big waves— the '65 Mustang could do it all.