My house was built in 1948 and is in St. Louis County, Missouri. I don't know what its walls are made of, but nothing is on them except paint AFAICT. For many of the walls, whenever I try to hammer a nail in, it won't go in more than a couple of millimeters or so; after that all I can do is bend the nail. Attempting to get into the wall with a drill or a "self-drilling anchor" yields a gouged-out wall rather than a clean hole. (The material inside, and gouged out, is grainy.) I seek suggestion, please, for getting something (preferably a nail) in my wall cleanly. (I simply want to hang some pictures!)
Most of the examples of this have already been painted over, so here is the only one I can find: it's the result of attempting to hammer a thin nail into the wall.