Wash and hull ripe strawberries, about 1 pint. Add a pint of sugar and cook over low heat. When juice begins to flow from berries, shake the kettle to mix juice, berries and sugar. When sugar is dissolved, increase heat and bring to a good rolling boil as soon as possible. Boil rapidly for 10 minutes. Remove kettle from heat, pour hot preserves into shallow trays or baking dishes and remove foam. Let set overnight for berries to plump. Next day, fill jars with preserves.