ok, you don't have any takers at all, and although I really don't have the answer either, I am, of course full of guesses.

what kind of trees flank the areas where you see them most? Are there ash trees/ Hickories? THe ash trees dropped their seeds a while back, but since they lie flat on the ground you might not notice them from a distance and it could look like the animals were instead munching rock. THe hickories are droppong early nuts too...some of our younger trees began letting loose of smaller nuts weeks ago and now the BIG NUTS are booming down. Could there be a pignut tree in the area??

If they aren't after seeds or nuts then I really have no idea what they're getting. Yop need to get as close as possible and really reaaly REALLY inspect this. THere is an answer to the riddle...you just have to go find it.

Thanks dirtgirl,
I'd almost given up on anyone answering this. I knew you would eventually be the one! :)
I'm wondering if they are sharpening their teeth????
Hopefully its not antifreeze droppings.
Its really weird! Their are a couple holes in the gravel that are about 2" deep! Is it like a salt lick for deer???
Are they trying to raise their pH???

Our wild rabbitts are very frindly, we talk to them & they sit within two feet from us. One of the adult rabbits is also eating gravel. It is not seeds, it is gravel.

We have the same issues with deer and rabbits eating the bank run drive way. Bank run is old river beds that occur in gravel beds. I always thought that there were minerals and salts that have collected over time that attracts them

I have a squirrel he does chew on rocks for several reasons.1. salt/mineral 2. Sharpening his teeth. Maybe your driveway squirrels are doing the same😁

I see the squirrels moving the rocks has to be something there. I do not have any trees close to my driveway.

Um, I think they might actually be blunting their teeth...which never stop growing during their lifetime. A balanced diet should ensure that animal teeth are kept in good fettle but creatures will replenish missing minerals and take care of their teeth, using what resources are available to them.

Thanks everyone! I just happened to look at this post and I started it 15 years ago! I appreciate all the responses. And yes, I'm still seeing the bunnies chewing things in the driveway. I think the teeth theory is a pretty good one. Thanks again!