Hi, I have been planning to write this particular tutorial for some time. So here it is finally. This tut is basically an exercise in painting texture from scratch having no dependency on any photographic material just to give an idea as to how far you can actually take PS. So let's start.
Open Photoshop :)
Take a blank image. Canvas size 400px X 400px
To make basic wood map we will use a gradient tool. Change the gradient type from SOLID to NOISE.
Apply the gradient and if it is colored make it Black and White by using DESATURATE.
Make a new layer change mode to COLOR and fill with a nice wood color. I will leave the color up to you.
If the wood map is too dark in some places use the dodge too in SHADOW mode to brighten up the map.
Now to make it look like wood. Select the background layer and apply the LIQUIFY FILTER. It should look like this afterwards. Sorry can't give you a screen cap of the liquefy UI. Print screen doesn't seem to work in that mode. But use the first button, and the twirl button. They seem to work bet. Avoid the bulge and Pinch buttons.