Here is a small and easy bowling pin material for blender. Advertisements
A short tutorial of how to create a apple material.
Here is the tutorial that shows how the wood material work on a node level. There is a lot of math involved but I hope you will be able to use it to get some insperation for your own material.
The first tutorial on material is ready. It can be found under the menu rock material. The name says it all, so hope you can use it. The final result can be seen here.