Interesting on the playsand! Thank you Iomine. I never use very much, I use mostly topsoil, but the sand seems to help break down the sometimes larger clumps of dirt. (I fill a plastic shoebox container...cheap at dollar stores!...about 1/3rd full of topsoil, then add maybe 1/4-1/2 cup playsand...
I haven't used coffee grinds, but I would be worried they'd eat it (because they will.)
I go to my local ACE and buy bags of topsoil and a bag of playsand. I mainly use the topsoil for them, but sprinkle a half cup or so of the sand on top. Then, when it gets full of shavings or dries too...