Complex sentence: Jonson recalled that he said nothing by "I and No", and they tried to place informers two informers Robert Poley and Parrot with him, whom are refrred to in his Epigram 59 "Of Spies".
Split into simpler sentences: Jonson recalled that he said nothing but "I and No". They tried to place two informers (Robert Poley and Parrot) with him; those two are referred to in his Epigram 59 "Of Spies".