Randomize Prefab Texture

Hello, I'm still pretty new to coding but I was wondering if there was a way to randomize the texture that is assigned to each prefab clone and how to prevent that texture from being used again if it has already been assigned to a prefab clone. This texture will come from an imported picture. I could manually switch the textures between two prefab clones with the code below but this may take awhile and cause the system to run slow because I want to use a grid size of 25x25, therefore I would have to copy the code 624 more times. If you are able to help me with this it would be greatly appreciated. Thank you.

 // create a new material using the defined shader.
             Material thisTileMaterial = new Material(PuzzleShader);

             // apply the puzzle image to it.
             thisTileMaterial.mainTexture = PuzzleImage;

             // set the offset and tile values for this material.
             thisTileMaterial.mainTextureOffset = new Vector2(1.0f / Width * i, 1.0f / Height * j);
             thisTileMaterial.mainTextureScale = new Vector2(1.0f / Width, 1.0f / Height);

             // assign the new material to this tile for display.
             TileDisplayArray[i, j].GetComponent<Renderer>().material = thisTileMaterial;
         }
     }
     // switch the second and third grid location textures.
     Material thisTileMaterial2 = TileDisplayArray[1,3].GetComponent<Renderer>().material;
     Material thisTileMaterial3 = TileDisplayArray[2,3].GetComponent<Renderer>().material;
     TileDisplayArray[1,3].GetComponent<Renderer>().material = thisTileMaterial3;
     TileDisplayArray[2,3].GetComponent<Renderer>().material = thisTileMaterial2;
    
 }

}