Note: This makes 4 jars of jam, I would say. When I made it, I halved the recipe but forgot to halve the lemon juice! It still turned out great, but on the runny side. I did not do the whole canning thing because we were going to use it right away and I wouldn't know what to do with a mason jar anyway.
4 cups mashed strawberries
4 cups sugar
1/4 cup lemon juice
You basically mix all three ingredients together, bring them to a rolling boil for about 10 minutes. Check the temp to make sure it reaches 220 degrees (F). Then place the mixture into sterilized mason jars.