Real World article(written from a Production point of view)
The sunflower was a flower native to the planet Earth.
Commander William T. Riker kept some sunflowers in his quarters aboard the USS Enterprise-D in 2369. (TNG: "Schisms")
Captain Jean-Luc Picard also kept some sunflowers in his quarters. (TNG: "A Fistful of Datas", "Chain of Command, Part I")