The catalogue of Edward Plunkett, 18th Baron of Dunsany (Lord Dunsany)'s work during his 53-year active writing career is quite extensive, and is fraught with pitfalls for two reasons: first, many of Dunsany's original books of collected short stories were later followed by reprint collections, some of which were unauthorised and included only previously published stories; and second, some later collections bore titles very similar to different original books.
In 1993, S. T. Joshi and Darrell Schweitzer released a bibliographic volume which, while emphasising that it makes no claim to be the final word, gives considerable information on Dunsany's work. They noted that a "ledger" of at least some of Dunsany's work was thought to have existed at Dunsany Castle. The Dunsany family has had a curator, Joe Doyle, since the 1990s, who gathered materials by Dunsany and Francis Ledwidge at Dunsany Castle, compiled writing and publication data, and unearthed works such as the Last Book of Jorkens and some "loose" Jorkens stories, plays including The Ginger Cat, and a set of short stories, some published in a 2017 collection, as well as supplying material for the Lost Tales series.
The following is a partial list compiled from various sources.
Lost Tales, Volume 1 (2012) Previously uncollected short stories appearing in magazines between 1909 and 1915.
Lost Tales, Volume 2: The Emperor's Crystal & Other Lost Tales (2013) Previously uncollected short stories appearing in magazines and newspapers between 1915-1920 and a previously unpublished story from 1909.
Lost Tales, Volume 3 (2014) Previously uncollected short stories appearing in magazines and newspapers between 1910-1954 and three previously unpublished stories.
The Men of Baldfolk & Other Fanciful Tales (2016) Five previously unpublished stories and four uncollected stories ranging from 1908 to 1955.
The Ghost in the Corner and Other Stories (2017) 50 uncollected and previously unpublished stories.
A Dreamer's Tales: Annotated Edition (2018) Annotated collection of stories
Lost Tales, Volume 4 (2018) Eight previously unpublished stories and one uncollected story ranging from 1909 to 1956.
Lost Tales, Volume 5 (2020) Six previously unpublished stories, two uncollected stories, one poem, and one story published in The Ghost in the Corner, ranging from 1914 to 1953.
Most of Dunsany's early plays were issued in individual editions by Samuel French and were freely available, though mostly for the acting and production markets.
A Glimpse from a Watchtower (1947), a long essay musing on the future in a nuclear era
Geography/history
My Ireland (1937), a non-fiction look at Ireland and her landscape and heritage, with photos
Autobiography
Patches of Sunlight (1938)
While The Sirens Slept (1944)
The Sirens Wake (1945)
Letters
Arthur C. Clarke & Lord Dunsany: A Correspondence 1945–1956. ed. Keith Allen Daniels. Palo Alto, CA, USA: Anamnesis Press, 1998, a posthumous collection with the cooperation of the Dunsany Estate and Arthur C. Clarke.
Books in print
Millennium Fantasy Masterworks
Time and the Gods (contains The Gods of Pegāna, Time and the Gods, The Sword of Welleran and Other Stories, A Dreamer's Tales, The Book of Wonder and The Last Book of Wonder, without the Sime illustrations and with Pegāna out of order)
The Dreams of a Prophet (hardcover, with large print edition also available via the Lulu.com website; contains the collections The Gods of Pegana, Time and the Gods, The Sword of Welleran, and Fifty-One Tales)