Sounds like you want stone that matches the natural outcroppings that are already on your land. Any stone left over from the excavation that preceded your construction that is likely to be similar. Locally quarried stone is also more likely to look like your existing stone. You might also be able to get stone from other construction sites in your area. Stone that is not cut into square or rectangular or standard geometric shaps will also look more natural but takes more skill to work with. You can go to a couple of stone yards to look around and see what they have. Finally, there are manmade products that look more natural than typical concrete blocks (but nothing beats the real thing). You can even get manmade products in a large variety of colors and textures. You could also use a thin veneer of natural stone over something less attractive to give it the natural look while having the function of manmade products.