Buckshot
Buckshot is like gravel, but finer and is generally more stable. Buckshot is sold as landscaping material is typically composed of fine 3/8-inch particles; some may be no bigger than a grain of sand. Colours may vary, from buff to brown, and include various shades of grey, black, red, and green.
Buckshot is best used in casing fill situations as well as a subbase for brick pavers. However, since it is small and round it will not pack in and always stays loose. Spreading it thinner will help it to stay in place better.