Something with a decorative edge made of repeated semicircles is scalloped. The scalloped hem on those curtains you made really suits the 1950s style of your kitchen.
You can use this adjective for anything that resembles a repeated scallop shell, like a little girl's scalloped skirt or the pretty pillows with scalloped pillowcases at your grandparents' house. When it comes to cooking, scalloped can describe a decorative pie crust, but it usually means "cooked in milk or cream or covered in breadcrumbs." This term probably stems from a tradition of baking this type of dish inside a scallop shell.