Ann Cox's book, Silk Ribbon Embroidery Designs and Techniques, shows a wall with moss on it...or maybe its lichen. Either way it's good for connecting my not-too-realistic wall blocks. And it adds interest and dimension.
I chose four colors of thread: 3 DMC cotton flosses and one DMC cotton floche.
The final moss wall...looks much better, and this technique is a great way to cover any ink bleeding (notice the wall top right between photo above and one below) or lackluster stones.
Now all I have to do is figure out what to tackle next. Iris, anyone?