Mafia 102. Veliria

Who knows. They say there is such a series.

Well, if we're talking about sunflowers, then in Samurai Champloo they were looking for a samurai who smelled like sunflowers.
https://ru.wikipedia.org/wiki/%D0%A1%D0%B0%D0%BC%D1%83%D1%80%D0%B0%D0%B9_%D0%A7%D0%B0%D0%BC%D0%BF%D0%BB%D1%83

Jin and Mugen are pondering that they have no clues about who this samurai is, who smells like sunflowers (c)
and this is much closer to the truth than just an anime about sunflowers, at least there is a connection with a samurai.
Moreover, the search for this samurai is essentially key to the plot; Jin and Mugen helped the main character search for him throughout the anime.