No you didn't dream it, and I'm guessing you might have actually seen the idea on a TV gardening show, that is where I was first made aware of this "Victorian" gardening style...
A stumpery is a garden feature similar to a rockery but made from parts of dead trees. This can take the form of whole stumps, logs, pieces of bark or even worked timber such as railway sleepers or floorboards. The pieces are arranged artistically and plants, typically ferns, mosses and lichens are encouraged to grow around or on them. They provide a feature for the garden and a habitat for several types of wildlife. The first stumpery was built in 1856 at Biddulph Grange and they remained popular in Victorian Britain.
Click to enlarge image...
Listed below are links to helpful and useful articles on the subject of "Stumperies":
Creating a stumpery
- If you live in the UK you can watch a video, if not, the page does list Ferns and Woodland Companion plants that can be used in creating a stumpery.
Who would have thought stumperies would be the next new, new thing in gardening? Stumperies hail from the 19th-century British Romantic Movement, which rejected the classical forms of the past while exaggerating the glories of nature.
Drawing on their love of ferns and the history of traditional stumperies, Pat and Walt Riehl of Vashon Island have created a modern version of this woodland garden. Among the many attractions are a tunnel entry and grottos full of tree stumps with their gnarly roots reaching for the sky.
Stumperies may be an acquired taste, as much historic and fantastical as they are visual. Yet they're the next new, new thing in gardening, pulled back from their Victorian roots and revived by Prince Charles, who in 1980 installed a garden of sweet chestnut stumps, ferns, and woodland plants at Highgrove, his country estate.
Good luck! and please report back here (post photos, etc) if you do decide to put together your own stumpery...