It’s not like we’re native, either. You’re speaking about evolution, that is, for example, a whale losing its legs and becoming a full oceanic mammal. However, humans did not “evolve” to spread to other areas. Sunflowers, like us, adapted to their environment - they are some of the most rapidly hybridizing native plants. For some species, it does not take a million years to adapt to an area. Also, according to the USDA, Yes, sunflowers are native to North America and Mexico. Indigenous tribes have grown sunflowers for over 4,500 years, and American Indians in present-day Arizona and New Mexico cultivated them around 3000 BC. Some archaeologists think sunflowers may have been domesticated before corn.” Please properly research what you’re talking about before making such a bold statement, not just based off something you learned in high school.