The name Posy is a girl's name of English origin meaning "a bunch of flowers". Posy and is often added to lists like Gorgeous Flower Names for Babies and discussed in our forums with posts like "Three Strikes, You're Out -- Girls".
From the experts:
A sweet, nostalgic nosegay kind of name, Posy has been long fashionable in England, a country of gardeners, but this pretty bouquet-of-flowers name is still rarely heard in the US, though it could be seen as a more unusual possible alternative to Rosy or Josie.
Posy is a little sister name in the Hunger Games series. Before that, Posy Fossil was a character in Noel Streatfeild's Ballet Shoes.
Posy (or Posey or Posie) could also work as a nickname for a range of other names, from Penelope to Sophia--it started as a pet form of Josephine. Other P-beginning flower names you may want to consider along with Posey: Poppy, Petal, Primrose.