Riley ate EVERYTHING
he could get in his mouth when he was a puppy, but luckily it all came out the other end, and he eventually "grew out of it". I have heard of dogs that have had bowel obstructions from eating rocks though, so I would really watch her, and call your vet if she stops eating / drinking or ( and I am no vet) if she stopped pooping. I would think that meant she had a blockage. We used a product called Apple Bitter. Apparently it tastes awful so we would spray it on things that we knew he was just dying to chew on, and it did seem to help. You said that it was a gravel area, so I am thinking you couldnt really spray the whole thing, but maybe if you just sprayed enough that she would get a taste???? Basically you are going to have to watch her, and single time she gets one, take it away, and say "NO" and/or "NON"
lol After 100 or so times, she'll get it.