• "Pattern Stamp Tool" lets you paint with a patterns.
• Photoshop contains some pre-defined patterns in the pattern libraries.
• You Can also create your own patterns and save it to the library.
• Specify the blending mode, opacity, flow and brush size in the "Options Bar"
• Try to paint a pattern with the pattern stamp tool, by opening a new blank psd document and selecting the required patterns.
• The Aligned gadget on the Options bar, when selected you can release the mouse button without losing the current sampling point. Upon deselecting the gadget the sampled pixels are applied from the initial sampling point each time you stop and start.

Video Tutorial: