Sentence:  But <WSD>cockle</WSD>, spurge, according to their law / Might propagate their kind, with none to awe, / You'd think; a burr had been a treasure trove. 
Meaning of the word marked with <WSD> tags:  Any of several field weeds, such as the corncockle, (noshow=1), and "Lolium temulentum".