In reviewing the Jack and Jill magazines I found in the July 1958 issue a Fae folk story called Billy Hook and the Three Souvenirs by Ted Hughes. I was able with a quick bit of online research to confirm that this was the same Hughes that was both the former Poet Laureate of England and former husband of Sylvia Plath. But I also came up with a bit of contradictory information: In one reference, page 164, of The Cambridge Companion to Sylvia Plath it states that Plath was co-author on this story while in a biography of Plath, Rough Magic by Paul Alexander it states (page 224) that this story was written by Ted Hughes alone.
These were the only two online references to this story that I found, hopefully I will find time to research this further.
I found a very interesting Horn Book article, quoted in part below, which actually cites Sylvia Plath's Journal and states that Ted Hughes wrote Billy Hook and the Three Souvenirs without any collaboration.
July 1958. Ted publishes his first story for children. Sylvia writes in her journal: “Vicarious joy at Ted’s writing which opens promise for me too: New Yorker’s 3rd poem acceptance & a short story for Jack & Jill. 1958: The year I stop teaching & start writing.” Sylvia regarded the acceptance as a kind of talisman, confirmation of their “promise” as writers. When the story is published, Sylvia writes in her journal: “In the A & P I rushed to the magazine rack & there was Ted’s story ‘Billy Hook and the Three Souvenirs’ in the July issue of Jack & Jill. The story was sumptuously presented: two fine lively color pictures & two half-tone drawings: gay & magic.”