Wash berries under cold running water & drain.
Coarsely crush berries one layer at a time using a potato masher. Measure out 9 cups.
Combine berries and sugar in large sacue pan & bring slowly to a boil, stirring until sugar dissolves.
Increase heat to medium-high and cook rapidly to gelling point (220F), stirring to prevent sticking.
Remove from heat and skim off foam if necessary.
Ladle hot jam into hot jars, leaving ¼" headspace. Remove air bubbles. Clean jar rim, add lid and rim and tighten finger-tight.
Place jar on elevated rack over simmering water.
Lower all jars into simmering water. Water must cover jars by 1 inch.
Adjust heat to medium-high, cover and bring to a rolling boil.
Process half-pint or pint jars 15 minutes.
Turn off heat and remove cover. Let jars cool 5 minutes in water bath.
Remove jars & allow to cool at least 12 hours on counter.
Check seals before storing.
(makes 6 half-pints or 3 pints)