flummery is both a fluffy 17th-19th century dessert pudding, and a load of nonsense.
‘It’s not the age of reason … it’s the era of flummery, and the day of the devious approach’ –Trouble with Lichen (1960)
https://en.wikipedia.org/wiki/Flummery
some incredible specimens here
http://www.historicfood.com/Jellies.htm
& a little on isinglas (swim bladders of sturgeon) which were a common ingredient in flummery
https://food-hacks.wonderhowto.com/news/weird-ingredient-wednesday-isinglass-or-why-your-guinness-has-fish-it-0161766/
a pretty basic recipe here, using berries https://permaculture.com.au/davidson-plum-rainforest-flavours-in-the-kitchen/
https://1tess.wordpress.com/2008/08/13/blueberry-gems/
https://books.google.lt/books?id=uCRdqi4lvK8C&pg=PA53&lpg=PA53&dq=blueberry+flummery&source=bl&ots=edOyqufQi6&sig=PMLJOx7XcWqKqtV8xYPuiGvQRNQ&hl=en&sa=X&ved=0ahUKEwiMx5Cfz9jbAhXBDywKHQ1lCmwQ6AEIazAO#v=onepage&q=blueberry%20flummery&f=false
http://www.cooks.com/recipe/2i8iz3ay/blueberry-flummery.html