IT may be hard to find the exact brown grass stuff, but moss would work well in that context, if what you had wasn't moss. If any garden stores in your area carry supplies for growing orchids you can find it there. There are several varieties of moss that are used for potting orchids. Some places might specifically sell dead spanish moss, but that's not the only kind that works. Spanish moss is also used to top of floral displays, so a floral supply place might have it. You could also try online. I know Lowe's Hardware carries the potting moss for orchids.
If you are going to wDW any time soon, there is a place just of 192 called World of Orchids that sells all kinds of supplies for orchids.
ooh, I think you might also find something similar to your original that is sold at places like Lowe's...I don't know how to describe it...It is sold as a mat to cover the area around trees - sort of like fake mulch or plastic tarping - to keep an area around the base of the tree from getting weeds. It's like a brown mat that you can put alone or under mulch. I don't know name ofr it, but it looks like the stuff they put in the planters.