I'm pretty sure that's a weed - I recognise those black markings but cannot remember exactly what it is at the moment - possibly one of the nightshades.
I had some of these grow from a pack of Cosmos seeds, I let them grow for a bit, definitely weeds!
Persicaria maculosa, Redshank. I think you can eat it (if you're desperate). I like it in the garden but it is a weed