Common restharrow (Ononis repens) is a creeping shrubby plant found in clusters close to the ground. It looks like a low growing vetch and is, indeed, a member of the same family, leguminosae, otherwise known as the pea family. Common restharrow particularly likes calcareous soils so it is well at home in Dorset and it can be found in flower on grasslands and downs across the county from June right through until September.
It is called 'common' because it is. indeed, the most common of the restharrows, the others (spiny and small) are far less common and are unlikely to be found in Dorset,
I have not been able to discover exactly why it has this name but there is a suggestion that when farm implements such as ploughs and harrows were pulled by oxen or horses these animals would browse on them whist the ploughman ate his lunch! I suppose this may be true but it seems that oxen and horses not would be that fussy and would eat a range of plants including grasses surely?