Shirtings are small prints with an ivory or white background that would be thought of as something a man's shirt would be made of. They are used primarily as backgrounds for busier prints. I have used shirtings many times as backgrounds for Civil War fabrics, i.e. with a design in the darker color and the background the shirting. Many online shops have them listed as a "shirting" category. They're sometimes kind of hard to find; especially since I won't buy fabric unless it's on sale, and they seldom are since they're in high demand.