In a nonreactive saucepan, over medium heat, combine the strawberries, sugar, pectin and lemon juice. Bring the liquid to a boil, reduce heat to medium-low and simmer for 25 minutes, stirring occasionally. Spoon the hot mixture into 10 (half-pint) hot sterilized jars, filling to within 1/2-inch of the top. With a clean damp towel, wipe and fit with a hot lid. Tightly screw on the metal ring. Process in a hot water bath for 5 minutes. Using tongs, remove the jars, place on a towel, and let cool. Test the seals. Tighten the rings. Store in a cool dark place. Let age for at least 2 weeks before using.