Flower or Weed!?

[Rogerbird]

Hi,

I am a complete beginner when it comes to gardening and bought a mixed box of seeds to grow for our little boy and the bees over summer.
There is this one flower that had grown much quicker and bigger than others and looks kind of like a weed with jagged leaves.

Please can you tell me if this is a weed and should be removed or is in fact a flower?

Thanks.

Roger.

 

[Rogerbird]

Forgot to add that the flower buds seem to be a dull shade of yellow that seem to stay closed and do not open up regardless of watering and sun.

 

[Mrsclem]

common sowthistle

 

[Rogerbird]

common sowthistle

Ha thanks.
So I've been feeding and caring for a weed!
Will dig it up tomorrow.
Thanks for the reply.