The best & easiest method I feel is to take out your camera (a mobile phone camera will also do for this one) and look around for the object with similar texture to what you are looking for, a cardboard, the wall of your room, tarmac, concrete etc. & click a picture. Desaturate it, control light & dark areas using curves to get just the right texture effect. Use that for masking creatively & you'll have a very original, non uniform texture.
Too Lazy!! Googling images for texture also does fine. But the above process leaves you with your own collection of textures in due time, just remember to name & tag them properly.
Hope this was useful. :)