Having obtained a copy of the poet's works, he proceeded at once to Grangerise them. Grangerisation is the addition of all sorts of things directly and indirectly bearing on the book in question, illustrating it, connected with it or its author, or even the author's family and correspondents. It includes autograph letters, caricatures, prints, broadsheets, biographical sketches, anecdotes, scandals, press notices, parallel passages, and any other sort of matter which can be got together as an olla podrida for the matter in hand. The word is from the Rev. J. Granger (1710-1776). Pronounce Grain-jer-ise. (See Bowdlerise.) There are also Grangerist, Grangerism, Grangerisation, etc.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894