Nori (海苔, のり) is a type of seaweed that use most commonly used to wrap sushi. Nori (also called laver in some English speaking countries) is made by shredding the seaweed into fine strips then drying into a sheet, similar to the process of making paper.
Nori sheets are sold in packages, and if your grocery store has Asian ingredients, nori should be available. Unfortunately there really is no substitute for nori, so if you can’t find it near you, you’re going to have to buy it online. But since it is a dried good, it has a long shelf life, so you can buy it in bulk and it will keep for quite some time!Buy on Amazon