A Cairn is a great choice for a natural, interesting and creative focal point in a garden. You may not need them as trail markers but they are eye-catching.
photo credit: Carly & Art
photo credit: loop_oh
photo credit: Wonderlane
photo credit: chefranden
The challenge is in building it. Thankfully, there are plenty of sources on the net to help with that.
Be aware when in public hiking areas that this form of expression is not smiled upon. the Acadia National Park has posted this:
I like this: “Cuiridh mi clach air do chàrn is a Scottish Gaelic blessing, which literally means “I’ll put a stone on your cairn.” The meaning though, is “I’ll not forget you.” The tradition is to take a stone and place it on another’s cairn as a memento of your visit.” from Our Little Acre.
And, don’t worry, you don’t have to be Andy Goldsworthy: