I bought a box of wildflower seed and everything but this has flowered. I thought it was an interesting plant but am now considering cutting them down - they have not flowered and have gotten huge. They are starting to look like ugly weeds.... If there is a chance of them producing pretty flowers soon I
http://www.southsidepreservation.com/PlantDatabase/DatabaseDetail.php?id=20 Here's the "weeds" in bloom.
They look like Cosmos to me too. I love Cosmos to cover up the foliage of spring blooming bulbs. I always scatter seeds among my Tall Bearded Iris, the Cosmos grow up, cover the Iris foliage and bloom beautifully. They shouldn't, however, be fertilized more than once, early in the growing season. If you over-fertilize you'll get lots of foliage and not many blooms.