You can easily make your own black/white patterns or mobile: Use a black marker to draw patterns on a sheet of white paper. You can do checks, zigzags, stripes, dots or stars. Cut the paper into small squares and glue one on each side of a piece of cardboard of the same shape. If making for a mobile, you may want to consider gluing aluminum foil to the back side of the cardboard (it will catch the light). Cover with contact paper.
Also see a unique website: fussybaby for a PowerPoint slide show of black and white designs for baby!