Homemade jelly is the best, and my kids favorite is blackberry. We picked several bags along the side of the road near our house over the course of a month and got over 2 gallons to make jelly. I froze the berries until it was time to make the jelly, or when I had enough. You want to have at least 5-6 cups of berries to start with to get juice. Cover berries in sauce pan with water snd bring to boil and cook for around 30 min. Bring heat down snd let simmer for another 20-30 min.

Strain juice using cheese cloth or thin cotton dish towel.

For the recipe you’ll need the following:
6 1/2 cups sugar
4 1/2 cups prepared juice from berries
1 box Sure Jell (fruit pectin)
1/2 tsp or little more of butter
1/2 pint jars with new lids and rings