How to model stone

If you want a stone look and texture, there is a filament called LayBrick.
Howwever, a cheaper and less problematic approach is to print it in any preferred filament, probably best at a higher resolution, then pick up some Rustoleum. They make a paint in a spray can that resembles stone.

Most commercial modeling programs have "textures" that do not offer actually real effects. It will give you the look of stone, but not actually have those qualities in the STL file.

Sounds like you're stuck making it yourself. Seems like you need to make the basic block, and then use some form of "geometric pattern" tools to repeat the pattern. It will look slightly stiff, since real stonework isn't perfectly uniform.

But if you really want the true modeled stone look, as it sounds you do, then it will require use of blender most likely. Sketchup is a geometric modeling program and not as well suited for the sculpting sort of operations that blender is better at.  autodesk meshmixer would also be decent at this, though I've never gotten the hang of it.

Is there any stonework around you that is similar to what you want?  You could use a camera and 123D catch to scan it, and use the mesh as a starting point.

As far as I know bump mapping doesn't really change the surface mesh, it only simulates surface imperfections during rendering, but leaves the actual geometry unchanged.

A while back I needed to make some cobblestone surface, and I used Solidworks to make a grid of stones, then used MeshLab to transform the stones into something more organic.

Here is the same technique applied to a set of bricks.  You can use any program to create the basic brick set, export it as an STL or OBJ, then use MeshLab to do the transformations to the mesh

I'm including the STLs, but you should probably do your own.

Sorry, I couldn't upload the last file, it's too big for the server (7.49MB).

What program? Not all can do that kind of work. I'm just curious. Thanks