Even when you are designing a very simple project with the simplest of the design templates, your design can be made to look different with the exclusive mud texture. Also, there is plethora of cracked clay textures available for free download and they can be easily used for any commercial or personal projects. Most of the time these textures are available as freeware but it is better to check the licence before using them for any commercial use.
Nature has been the best teacher for all of us. No matter how simple it is, there is always something to inculcate into jpg or png format depicting the natural resources. So features like cracked mud, nasty cracks, dirty sand, shabby mud etc. are some of the common textures which can be inculcated into designs to make them give a real look. For instance, a cover of geography book or a topography magazine can have any of the above textures to give it a realistic look.
As you select from any of the freeware texture available, it is very simple to edit and customise the texture as per your requirement. As you need to do is find the proper filters and adjust the edges or the colour gradient or any other factors whichever you think needs to be fixed. Sharpen the cracks or the dirt on the ground to make it look smarter. Saturation, lightness, stylisation can all be controlled with Photoshop and digital print can be created looking as realistic as possible.