I think the "pretty flowers" line refers to the field (feild... however the heck you spell it) of paper flowers. The paper flowers symbolize innocence, and they're pretty, and now Amy is leaving innocence in the dust.

Usually I'm really not into anything remotely sexual, but this song... I just like it. It's not explicit, it's pretty subtle, but it's so awesomely dirty. Not like you're trying to be that way, but it just has this freedom to it. I like that.