Hi Robin, and
to ATP. That particular iris is very popular and usually available at almost any good nursery. (not a box store, a real nursery) Just look for the striped, variegated leaves (because it only blooms in the springtime). There are two types, Variegata and Argentea, but the first one is the most common. It has cream and green leaves and Argentea has white and green, with paler blue flowers.
You're right, it is I. pallida 'Variegata' Here's the link to it in our database.
Species Iris (Iris pallida 'Zebra')