Golden Melilot is one of two biennial yellow Melilots found in the British Isles, both of which may have been introduced in Roman times or before for use in poultices. The species are difficult to distinguish as the plants are very similar, have similar distributions (mainly England), and can grow to similar heights. In the case of the Golden Melilot flower the keel, wings, and standard are all similar in length (photo), while for Common Melilot (Melilotus officinalis - AKA Ribbed Melilot) the keel is shorter than the wings. In the (probable) case of doubt "Melilot" is a pretty good identification!

Flower: Little yellow "pea" flowers about 5 - 7 mm long in numerous little to big spikes.
Leaves: Oval, toothed, usually trifoliate.
Habitat: Waste ground, waysides, coastal areas.
Height to about 1.5 m
Typically flowering: June -  August