I heard about doing this somewhere, so I decided to take a crack at it.
I saved up a weeks worth of coffee grinds, which filled about three of these containers:

spread them out on a cookie sheet and baked 'em at 350 for about 25 minutes and whamo:

ground cover.
The baking dried them out thoroughly and it is nice and powdery. I can use this as a base, and intersperse greenery through out, or I can use it as bulk and cover it completely. Either way, I drink enough coffee that I can put the remains to good use, and they’ll smell good too!
Didn’t net a whole lot once the water got steamed off - but it’s a start:

Just sharing how well it worked out, it might be old news
add powdered creamer to it for snow. [:D]
Mix some sugar with water and make glue.
I am saving my coffee grounds for now on!
Jim H
Dan writes: “Will there be a bug issue??? Or do they not like 'em? I’d be afraid of ants or worse on my layout.”
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The brown ants could simulate rabbits and the head lice could mimic beagles chasing them.[:D]
seemed like a good idea at the time. If I read between the lines correctly, I perceive it was a not so good idea.
Do ants or bugs like coffee?
Jim H
Frank,
We’re just having fun. Railroaders in the past have done the method you suggest. However, I think you’d be better off with clay-like soil (perhaps cooked to get rid of critters). That’s what I’ve used. Others have used brown sawdust or groundfoam.
The coffee would work but ensure it’s dried out or fungus will be present (from personal experience)
I have done this , some months ago, so far so good. No bugs no smell. Also have taken dirt out of the back yard , dried it in the oven and kept a large supply on hand for ground cover over paint, also works pretty well.