Every Japanese "Zen" garden has at least three stones, a Buddha stone (which is upright), a horizontal stone, which is said to represent the earth, and a diagonal stone which represents humanity.
I have abandoned my cherished idea of a raked sand garden out front, primarily because keeping it free of the petals, catkins, berries, leaves and other debris which falls from the overhead trees would be a nightmare. But I kept the idea of including Zen stones, surrounded by moss.
I have my diagonal stone, one which Ian and I found on a hike and (bless him) he packed back to the truck for me. It's large and heavy, so that was a labour of love. It's been in the garden since we first moved here, looking more at home every day as the moss creeps up around it. I may fiddle a bit of moss into the cracks, though doing so will hasten its demise. One large slab of it already fell away with the freeze and thaw cycles of spring.
And at the end, in lieu of a Buddha stone, is a stone Buddha. While I am not one for many garden ornaments the Buddha isn't an ornament (is he?). He lifts his hand in a gesture of acceptance and mercy for all sentient life and extends an aura of calm. He sat on the earth last season. He now sits on a two-inch thick slab of white quartz brought by a friend.
The vertical or earth stone in many Zen gardens is boat shaped. I suppose you could extend the analogy to that of the earth as a ship or boat. I had not found a suitable stone boat, but sitting in Jerry's abandoned rock garden was the perfect one. Hence my begging.
He sort of grinned and said to take it if I liked it. I got Tony to lift and carry it to its new site, as I couldn't budge it. (Granite is heavy!) I replaced it with two smaller stones so there wouldn't be a gap in Jerry's ring, and skipped home happy as a clam.
So now we are all properly Zen-i-fied. I dug a hole for it, as much as I could, considering the tree roots, snugged it in between some plants and planted moss around the bottom. Within weeks it will look as though it has been there forever.