I think it is some kind of flower.

Hmmm, I won't swear to it but it looks suspiciously like a Ragweed seedling.
The young leaves can vary a bit in how they look but if it starts showing the typical ragweed leaves then rip it out!
Here's a seedling pic with leaves a tad younger than yours:
http://www.lsuagcenter.com/MCM...

Hopefully someone will chime in with a happier suggestion!

Ragweed leaves are usually hairy.

Do you have any Dahlias nearby? I have grown them from seed, and even in this cold climate I get them setting themselves around.

It's the first two leaves, cotyledons, which are the main clue here but plenty of Dahlias have true cut leaves, I have some. It all looks like Dahlia to me but you will find out when it grows bigger, it will become more obvious and they can flower in the first year from seed.

http://www.shutterstock.co.in/...