Helianthus is a sunflower - they are beautiful!
I've never seen one. Do they grow tall?
I think so, and they are native to north America.
I think I've eaten the seeds in the past. 
The common sunflower is also "Helianthus annuus"
Funny name. You know a lot of about them. Do you have a flower garden?
tropical regions as food crops for humans, cattle, and poultry, and as ornamental plants. The species "H. annuus" typically grows during the summer and into early fall, with the peak growth season being mid-summer. 
Perennial sunflower species are not as common in garden use due to their tendency to spread rapidly and become invasive. The whorled sunflower, "Helianthus verticillatus", was listed as an endangered species in 2014 when the U.S. Fish and Wildlife Service issued a final rule protecting it under the Endangered Species
Helianthus
Helianthus or sunflower () is a genus of plants comprising about 70 species. Except for three species in South America, all "Helianthus" species are native to North America and Central America. The common name, "sunflower", typically refers to the popular annual species "Helianthus annuus", or the common sunflower, whose round flower heads in combination with the ligules look like the sun. This and other species, notably Jerusalem artichoke ("H. tuberosus"), are cultivated in temperate regions and some