Mini Pellia liverwort, Riccardia Chemdryfolia (Coral Moss)
Pelia does well in a variety of different areas of the tank, whether you want it as a foreground or background plant. Though not an actual moss but a liverwort (similar to Riccia), it is very easy to attach to hardscapes.
This comes attached to a 1.5" x 1.5" stainless steel mat, making it much easier for placement during your aquascape tank design!