Golf IV R32 :: Medium-weight Rattle Coming From Driver Side Front In Wheel Well Area

In the last few months my car has been making this crazy medium-weight rattle sometimes, meaning it doesn't sound like something really light doing it and it doesn't sound like something heavy doing it either. Its "history" went like this:

Noticed this sound that really seemed to be coming from the driver-side front, in the wheel well area, checked it out. Nothing obvious. Had the front of the car on ramps a couple of times, poking, prodding, grabbing/shaking things. All is tight. Then had it on stands; same routine, same results. It got a bit worse over time, though it doesn't ALWAYS do it! Sometimes it's quiet forever (on 90-minute drive last week, nothing). This evening, out for 20 minutes, lotsa racket. So it comes and goes. Nothing under the hood seems amiss, either.

At first it seemed to only be present when moving, like something rubbing or dragging on a tire. Nope. Then it seemed to be related to engine speed, like some under-hood component checking out and starting to fuss. That seems not to be the case anymore, either. Now, I've been able to discern that it's something come loose and VIBRATING (I'm pretty sure -- it just sounds like that), but I don't know what yet. I now hear it at idle, sitting at a light (sometimes) and it's definitely worse on rougher pavement than on smoother pavement.

A while back I realized that it must not be coming from outside and under the car after all, because putting the window/s down results in not being able to hear it at all, rather than being able to hear it better. This is true even at 5 mph, rolling along on a quiet street entirely for diagnostic purposes.

Earlier this evening (during the 20-minute out n' about), I note that it's not coming from the driver side anymore; it's more like the whole front of the car. Really seems to be under the dash. When I first figured out that it's NOT outside/underneath, I took off the panel under that side (three Torx screws) and poked around. Didn't find anything obviously loose, etc. I've ruled out the glovebox, its door, and the center console, by holding on to each while rolling. The sound is not quite in the correct spot to be from any of these, either.