Flaveria bidentis

Flaveria bidentis, the coastal plain yellowtops, is a South American plant species of Flaveria within the family Asteraceae. It is native to South America, and naturalized in many places.
In the U.S. it was introduced into the states of Georgia, Alabama and Florida.
Flaveria bidentis is an annual herb up to tall. One plant can sometimes produce 100 or more flower heads in a tightly packed array. Each head contains 3-8 yellow disc flowers. Sometimes the head also contains a single yellow ray flower.