Gophers are rodents that can be found in the area. The "true gopher" (as opposed to ground squirrels that are sometimes called gophers) are called "Pocket Gophers" (pocket in reference to their cheeks).
They like to burrow and are consummate hoarders. They use their cheek pouches for transporting food back to their burrows. These pouches are fur-lined, and can be turned inside out. They extend from the side of the mouth well back onto the shoulders.
Gophers like moist soil and their presence is marked by the appearance of freshly dug mounds dirt in your garden or lawn. They also enjoy vegetables and some species are considered agricultural pests. There are methods for exterminating the pests from your organic garden at Gopher Manifesto.