Whatever you try, please provide photos!
I've been using tea lately for my ground cover, either loose or open some bags. Depending on what season you are trying for, I've used orange spice for fall, black tea for a nice dark base, etc. Look at what teas you have and open a bag to see how it looks. Spices work well also, if too big, just grind them up.
A caution on teas, when I first used glue to seal it, it was too wet and caused the tea to run somewhat. Easily fixed and I actually used that to my benefit on another project where I had some reddish tea run to look like a blood stained turf.
Do a search for spices here in the onering and you will get some other ideas.
Here are some threads to look at
viewtopic.php?f=7&t=31501&p=402487&hilit=spices#p402487viewtopic.php?f=7&t=31952&p=408205&hilit=spices#p408205