The English Pea: Pisum sativum (Latin)
From the Missouri State University plant Entomology Homepage:
The English pea (or garden pea) is a cool-weather crop and requires large amounts of moisture. Production for fresh market in the winter and early spring in southern areas has declined, replaced by canned and frozen peas. Peas are grown throughout the U.S. during the proper season as a garden crop. Commercial production for canning and freezing is concentrated in the Northeast, upper Midwest and the Northwest. Seed are produced in dry areas in the upper mountain states and in California.
For cooking purposes in the United States, these are just plain old green peas. They can be found in your nearest grocery store, supermarket, or organic food shop.