Most people don't use starch any more, but there may come a time when you need it. You won't need to take a mad dash and some cold cash to a store if you have a few grains of rice on hand. White rice works best.
Boil about a tablespoon of rice in a couple of cups of water until the water becomes cloudy, then strain the rice and add the water to a gallon or two of clear water. Dip your clothes or linens in it and dry part way before ironing.