Since they were so tall, I'm gonna guess they might hv been canna musafolia, a beautiful canna. It is supposed to be hardy to z8, not 7 where you are. I would suggest digging at least a couple of rhizomes and protecting until next spring, just in case what you leave on the ground doesn't survive winter. I would further uggest cutting the restt now, covering with mulch or straw or whatever you guys use to protect tender perennials/tropicals and wait til spring.

You could let them be but then you'd have the ugly dead foliage during holidays. why not clean now before it gets colder?

I live in zone 6 and managed to overwinter mine outside this past winter.....I cut them down and added 2 feet of dry grass clippings ontop of the bed...then I put a tarp on top of that and weighed it down with some bricks so it wouldn't blow away....