edible weed - sweet and sour ? ID needed

Hi, I would like to id a weed that grows in Richmond fields (notably cow pastures) which I know as 'sweet and sour'. It has a mostly sour taste, but nice. It has elongated spade leaves, and a thin stalk of red and green seeds. Tends to grow on dry bare areas or in the pasture. I believe it is natural to the area. Attached are two photos of the plant when it is young.

 

Probably common sheep sorrel, sour dock, Rumex acetosella

 

Thank you so much, it is sheep sorrel!