In this tutorial I will show you how to create a really nice, realistic wood texture which you can later use to texture 3D models. Follow below steps to find out more:

1) Let's start by creating a new document and creating a rounded shape with the Pen Tool as shown in figure 1.

2) Now let us fill brown color (which should not be too light nor too dark) to the newly created shape as shown in figure 2. I have selected RGB: 146, 94, 29 for this tutorial, which would be a color similar to wood.

3) Now holding control key click on the shape layer to obtain a selection which has the same contour as the shape. Then add a new layer on top of the previous one. Now select Gradient Tool from tool pallete, click on the color gradient on the top bar and choose Noise as Gradient type in the Gradient Editor dialog box as shown in figure 3. Hit Randomize to change the colors.

4) The resultant image would be as shown in figure 4.