Stone and Bricks free materials (Link on comments) : r/blender
Stone texture by anul147 on DeviantArt
Procedural Stone Material (Blender Tutorial) - Tutorials, Tips and Tricks - Blender Artists Community
procedural irregular stone/brick wall texture - Materials and Textures - Blender Artists Community
Blender Market - Realistic Procedural Granite Stone Shaders for Blender 2.8 EEVEE + Cycles. You get 2 ready-to-use material groups, "All Purpose" Granite (typically gray) and "Meissner Granite" (typically red). https://buff.ly/2JBobD7
cycles render engine - Creating a procedural stone texture - Blender Stack Exchange