Since buckwheat hulls are prone to caking, they should be applied no deeper than 2 inches. Forceful watering will cause scattering of buckwheat hulls. These are brown, light, easy to handle, and relatively noncombustible. Cocoa shells have some value as a fertilizer and resist blowing in the wind. Their high potash content harms some plants, so they should not be applied to a depth greater than 2 inches.
Coffee grounds contain some nitrogen.
This is a good mulch, as it has fertilizer value and soil-like appearance. It is also a good organic amendment for tilling into the soil after the growing season ends. Ground corn cobs are a good mulch. Some find their light color objectionable. Other uses for ground corn cobs, such as in feeds and mash, tend to limit the supply for mulching.