Making rocks on the cheap
We start with one piece of geometry (a cube interpreted as a subdivision surface), duplicate it 3 times and scale each of differently them to get different shapes.
We setup a texturing network using PxrRoundCube...
...and make our first render.
As we are using a single stone texture, we can see similarities between our rocks. We could use more textures but we are doing it on the cheap ! Let's add displacement, using the same PxrRoundCube.
This is starting to look better : our stones all look different now ! Still, if you look at the bottom of the right-most stone, the stone grain is not oriented the same way as the top of that rock. It looks a bit un-natural.
This is easy to fix. That area corresponds to the Z axis, so we go to "Z Axis" section and toggle "swap ST". This is equivalent to a 90 degrees rotation of the texture on the Z axis.
They all look different and reasonnably natural. We've earned that coffee !