This was a pattern I created for a recent project. You are free to use this pattern however you want.
To use the pattern in Photoshop you will need to install the included .pat file. If you are not familiar with how to do this, you can check out this tutorial video. You might want to scale the pattern respective to your canvas size to achieve the best results.
To use this pattern in CSS just add background: url('masonary-pattern.png') repeat; to the element you want to display the pattern in. Just make sure the url points to the valid location of the pattern image.
If you want to create your own similar pattern, you can learn how to do it from this tutorial.DOWNLOAD