In reading through Richard Herring's Paper and Paper-Making Ancient and Modern (London, 1855) I found that Herring made a critical comparison between paper made by hand and paper made by machine, and also included in his book samples of hand-made paper and machine-made paper so that users of the book could make comparisons. Herring's comparison of the two paper-making modalities may be the first published in English, and is also most probably the first to include samples. The first edition of his book Herring included 25 samples, several of which he indicated were made specially for the book. The samples are numbered in the book; there is no list of samples. Herring refers to each sample by number within the text.
In the second edition, published the following year Herring included 30 samples. In the first edition the first sample was a sheet with a large and elaborate watermark that included Richard Herring's signature. The subscriber list to the first edition included about 160 names and it is possible that the first edition was not very large since a second edition was called for the following year.
Besides this work, which underwent three editions by 1863, of which only the first two contained original paper samples, Herring published a more extensive work in quarto format with as many as 246 paper samples:
A practical guide to the varieties and relative values of paper; illustrated with samples of nearly every description, and specially adapted to the use of merchants, shippers and the trade. To which is added a history of the art of paper-making. London: Longman, Green & c., 1860. Princeton University Libraries described and illustrated a copy at this link.