I will confirm that there are many of those hidden burial sites on Find A Grave and, if you know of one that isn't there, you should add it. I have adopted an older cemetery in my town and, along with others, are getting it fully photographed. When you create your profile, you can volunteer to take photos in your area. As someone who has worked it both as a photographer AND as a family member searching for a headstone, it is WONDERFUL. You are needed.\ if you haven't already done it. I know your post is old but maybe someone else will find this important.