This is a wildflower called Verbesina Alternifolia - its common name is Wingstem, because its stem has flat bits extending off it all the way up - sort of wings, I suppose. It grows all over the place at this time of the year - including in my so called flowerbeds because I've been too lazy to really weed, and besides, I'm sure the birds and bees love it. It's a very tall plant - the flower bits at the top are often at eye level, if not over my head. Apparently some people call it "yellow ironweed" because the plant itself is somewhat similar - although the flowers certainly are not. This page shows some nice photos of the stem as well as the flowers.