"Yarn bombers target anything they find from sleeves on parking meters, trees, statues, to cars and buses. Like most graffiti artists, this group of knitters often tag covertly in the middle of the night. " From Yarn Bombing: The Knit Graffiti Movement - Apartment Therapy
I have found one sample of yarn bombing in Fort Worth, however capturing the knit wrapped traffic sign at IH-30 at Hulen will require a driver for this photo op.
Take a look at what those crafty ladies have covered in metropolitan areas around the world. Images