One of the items in the Big Bonhams auction back in 2018 was a wallet containing seven membership cards (Lot 330) to various organizations such as the Boston Public Library, her drivers license, the Poetry Society of America, and an insurance card with Mutual of Omaha (see this post, if interested). The winner of the lot has been selling the cards off one by one. They have appeared in various auction houses (Nate Sanders last December for $1500), Barneby's for $7,500!, and ebay) and formats since that time. At one point some where being offered for obscenely unrealistic prices. Most have sold, I believe.
Minutes ago, Plath's insurance card with Mutual of Omaha was offered for sale via Heritage Auctions. It is signed "Sylvia P. Hughes" and Plath has also filled in her husband's name. The back of the card was filled out by Aurelia Schober Plath as the emergency contact person and includes Sylvia Plath's religious affiliation and blood type which was O. As a straight-A student, I'm sure she was happy getting an O on her blood type, than a B.
The card sold for $1,300 ($1562.50 including buyer's premium). Congratulations to the winner.
My thanks to Jett Whithead for alerting me to the auction.
All links accessed 12 November 2020.