Your search for "printed cardboard" revealed the following:
12x12 Chipboard - Black
$2.99A single 12 x 12 sheet of sturdy, black chipboard is ready to be altered for scrapbooking, card making, banners,...
Spooky Words on White - Cardstock Paper
$12.00Halloween: Spooky Words on White cardstock paper. (12x12) (15pc.) CCP2230