making a grid of buttons each with different textures

Hello, I creating a grid of buttons using NGUI, however I want each button to have a different texture. I am unsure of how to do this. Any help would be greatly appreciated.

Im not very familiar with the NGUI plugin, but maybe you can try to implement some GUITexures, assign diferent textures for each and create a prefab of eachone then you can Instantiate them and position each one independently y code.