Is it a herb?i.d plz

I planted what i thought was all herbs form my pots into a large half barrel months back but i dont recognise this one so not sure if its a weed ? thanks julie x

 

Not too sure about this one Joolz, but it does remind me of a couple of familiar weeds; Redshank is one, Knotgrass is the other.

 

Thanks trunky,its in a clump and i cant see anymore on the garden so its confused me,il google redshank n knotgrass and check them out x

 

No its no them,i will try n take a better photo of the leaf shape that might help

 

Some sort of Persicaria?

 

Thanks marley,its looking like sheeps sorrel by the look of the bottom leaf shape ive no idea where it as come from i cant find my basil thou x

 

Id gladly swap it for one