Laura Sutcliffe, 42, works as a crochet patter designer and has been making the toppers since the first lockdown in 2020.
She placed them on a post box outside the Sandford Nursing Home in Church Stretton in the hope of raising smiles from the residents.
However, the one placed outside the Nursing Home disappeared between 6am and 9am on Monday morning.
Laura has now said that the theft has "taken all the fun out of making the toppers" and does not want to make anymore until the stolen item is returned to the post box.
Laura, a mother-of-one, said: "Before the jubilee I had made eight toppers to mark various events or seasons, and these had been really well received.
"I had collected them in again with no problems and I published the pattern for a crochet crown in the run-up to the Jubilee.
"I decided to incorporate this design into a series of three post box toppers to put on various ones around Church Stretton.
"The pattern sold hundreds of copies and I saw photographs of crowns appearing on post boxes and in window displays all over the country.
"I put my own three toppers out in Church Stretton in early May and included donation details for Cancer Research UK.
"This is a charity that is close to my heart after I lost my mother, Dot Mansell, to breast cancer in May 2017.
"The charity collection has raised just over £1,500 in total.
"Sadly, I went to collect my toppers on Monday morning, only to discover that one of them has been stolen.
"I was hoping to sell the topper to raise further funds for charity so I am really disappointed that someone has just helped themselves to it and hope that this appeal will see it returned to the post box.
" I am so upset that this has happened that I am not going to make any more toppers until it is returned."