I never make this connection between nami and sunflower. But I have a theory that luffy's mom name is hima or himawari (sunflower). Because I believe she is from amazon lily and every woman from amazon lily has a name of a flower. But the fact nami symbolizes sunflower is another proof of luna
Actually most of the female character in one piece is name after flower or Bird.
This is not unique to Amazon Lily.
I believe Luffy's mother is celestial Dragon.
Shanks is son of Rocks d xebec and Figarland
Luffy is son of Monkey D dragon and Don Quixote
Luffy's hometown is Fusha (Windmills),
Windmills and Don Quixote
"Don Quixote bravely charges the giants until he gets too close and one of the windmills knocks him and Rocinante, his horse, over. At this point, Don Quixote realizes that his foes are indeed windmills. Instead of admitting his mistake, he decides that some sort of magic changed the giants into windmills "