This is anise hyssop, a delightful plant. The leaves and flowers have a wonderful smell. Tea from the flowers is delicious. Just make sure you rinse well to remove any small bugs! I don't make jelly, but I suspect the tea would make a very nice lavender tinted jelly. If you closed your eyes you could identify this plant from the aroma it releases when touched.
Anise hyssop grows well, blooms for a long time, and the little chickadees and finches love the seeds.For drying removal of the flowers while they still retain their lavender color is necessary. Here they self seed with abandon, and join the legion of perfectly good plants to be weeded out in the spring.