Recently I bought a little booklet, Kate Sargeant's One Hundred Mushroom Receipts, published in 2006, by Fred Kelso, Hengwrt Publishing Company, Lewisville, Pennsylvania. It is a reprint of the original book, published in 1899 by Charles Orr, Cleveland, Ohio. It is presumably the first English language cookbook dedicated to the little mushroom. In Mr. Kelso's introduction, he mentions "there were no other mushroom cookbooks published until Countess Morphy's 1938 Mushroom Recipes".
So I had a look in the library here at Kitchen Garden Books and came up with some other titles to add to a bibliography. In Lavonne Brady Axford's excellent bibliography, English Language Cookbooks 1600-1973, there is a list of more than two dozen books about mushroom cooking, some more contemporary (not included) and she was so useful in compiling this list.
William Rubel of Santa Cruz, California contacted me recently with several excellent additions, noted by an *asterik. He recommends those marked with the pound sign# as being particularly important. Thank you William!