Jessie Laidlay Weston (1850-1928) was an independent scholar and folklorist, working mainly on mediaeval Arthurian texts.
Her best-known work is From Ritual to Romance (1920); this book is now available as an online text, as are others of hers. In it she brought to bear an analysis harking back to James Frazer on the Grail legend, arguing for origins earlier than the Christian or Celtic sources conventionally discussed at the time. It was cited by T. S. Eliot in his notes to The Waste Land. (He later claimed that the notes as a whole were ironic in intention, and the extent of Weston's actual influence on the poem is unclear. Eliot also indicated that the notes were requested by the publisher to bulk out the length of the poem in book form, calling them "bogus scholarship".)
It also caused her to be dismissed as a theosophist by F. L. Lucas, in a hostile review of Eliot's poem. The interpretation of the Grail quest as mystical and connected to self-realisation, which she added to the anthropological layer of reading, was to become increasingly popular during the 1920s. According to Richard Barber in The Holy Grail: Imagination and Belief, the Wasteland as theme in the Grail romances is of minor importance until the last works of the cycle, and the emphasis on fertility is "an interpretation which has haunted twentieth-century literature to a degree quite disproportionate to its basis in fact". The book appears in the film Apocalypse Now amongst those kept by the character Kurtz, along with The Golden Bough. Kurtz quotes the end of The Waste Land before he is killed.
While Weston's work on the Grail theme has been derided as fanciful speculation in the years since the publication of From Ritual to Romance (even one-time supporter Roger Sherman Loomis eventually abandoned her hypothesis), her editions of numerous medieval romances have been commended as valuable translations. 
A biography "In Quest of Jessie Weston" by Janet Grayson appears in "Arthurian Literature," Vol 11 (1992).