Do you mean the round style river stones? These are very common in Nakhon Nayok and used in lots of houses. I think the method is like what you describe, with the concrete structure. Although I think (but not sure) sometimes they are used in place of bricks and then rendered on the inside to leave a smooth finish.

They are often used for the lower part of the walls, while the upper part is just the regular brick and render. This may be due to the weight of the rocks (bloody heavy).

If you go to NN and drive up to the dam you'll see quite a few places done like this. Below is a pic of a half finished place where it looks like they've run out of money and stopped work. Is this the type of stone you meant?