I use this as a basic recipe for alot of different jams, it's how my grandma made it before they had pectin.
Use scant 2/3 cup sugar per 1 cup of berries.
Use whole blueberries, raspberries or wild strawberries, cut up any other kind of berry or fruit you use.
Just heat up slowly to form a juice then boil for 20- 40 minutes depending on how thick you want your jam. Seal up. Juicier berries or fruit take the longest to cook.