I have just mentioned a few mulches that you can find on the market. In addition to the ones mentioned you can use gravels, colored mulch which is ground up used pallets and dyed, rubber mulch which is ground up used tires, leaves, grass clippings, sawdust, and wood chips.
Let me caution you about using mulch with a high content of wood or un-decomposed leaf matter. The fungi that decompose wood and leaf matter require a lot of nitrogen to do their thing. This nitrogen is absorbed from the soil below the mulch. The depletion of soil nitrogen can be extremely detrimental to shrubs and trees growing in the raw mulch.
When you mulch use about a three to four-inch layer. Make sure you keep the mulch an inch or two away from the stem of trees and shrubs. If you put the mulch up on the stem, the stem will slow rot due to all of the excess moisture, and your trees and shrubs will slowly die.
Mulch is not always a cure all. Its presence can cause problems. If your area is naturally wet, layers of mulch will inhibit soil drying. Plants in that area can actually drown during wet seasons.
Be sure you know what the mulch will do to soil pH, and the pH requirements of the plants in your landscape. As mentioned above, pine needles will reduce the soil pH to about 5.0. Hardwood bark mulch usually keeps the pH around 5.5 to 6.0.
One other problem shows up in hardwood bark mulch. Sometimes fungi grow on the mulch in warm wet weather. This disgusting looking fungus looks like an animal vomited in your landscape. In order to reduce this problem, occasionally stir the mulch to allow air to get into it. This should reduce the fungus problem. I have given you a lot of information about organic mulch. I hope this helps you select the right mulch for your landscape.