Tooth extraction, bone graft, dry socket?

Without photos or xrays it is not possible to tell what kind of bone graft you have. Often you can't see the graft material in a socket as it looks like food or white film over the socket. You are correct sometimes it does come out and often feels like sand in your mouth. It can be replaced in a few weeks after the extraction if necessary.

Hi:Unfortunately without photo and X-ray it is difficult to give you accurate advice.  Please post photo and X-ray of the affected area.
Best,
Dr. Maddahi

Go see your dentist to make sure everything is ok. It's possible that it could be ok. I'm guessing you are not having any pain. If you are and , or you don't feel assured that everything is ok, Then I suggest you get a second opinion.