The ornamental design for a wallpaper with pattern, as shown and described.
FIG. 1 is a top plan view of a wallpaper with pattern showing my new design; and,
FIG. 2 is an enlarged view of the area circumscribed on FIG. 1.
The broken line surrounding FIG. 1 represents the boundaries of the wallpaper with pattern and forms no part thereof. The sides and bottom surfaces of the wallpaper with pattern form no part of the claimed design.