It isn't as awful as
Poppy and
Pansy, but it has a similar cutsy childishness.
Posy would work as a name for a newborn lamb or a bunny.
It also has some dark undertones since medieval people would stuff their pockets with posies during the plague.
Ring-a-ring-a-rosies
A pocket full of posies
Ashes, Ashes
We all fall down
It might lend itself to a horror flick.
Posy would be the winsome girl who is all ribbons and bows until it is revealed that she is trying to kill everyone. *que horror music*