Old-Fashioned Strawberry Preserves

Place hulled strawberries in heavy large saucepan and mash coarsely. Cook strawberries over medium heat until beginning to thicken, stirring frequently, about 6 minutes. Reduce heat to low. Add 2 cups sugar and stir until dissolved. Increase heat to medium and boil gently until mixture thickens and mounds on spoon, stirring frequently, about 20 minutes. Remove saucepan from heat. Cool. (Preserves can be prepared 1 week ahead. Refrigerate in airtight container.)