Yes Jamie, they did. It was just a little shop in the neighborhood, owned by a couple of women. They were happy to save them for me. I'd take a nice clean 5 gallon bucket with a lid, they'd add the grounds and filters. They'd fill it it 2 to 3 days. When I went to pick up, I'd deliver a nice clean 5 gallon bucket.
Starbucks has a policy of recycling their grounds. They don't do it around here, though. (And there are none in my area, they're in more upscale areas than mine!). You can google "Starbucks grounds for your garden" to find info.
If you really want to understand composting, the ratios, the phases, etc, you might consider reading Teaming with Microbes, a Gardener's Guide to the Soil Food Web by Lowenfels and Lewis. Very good, very complete and informative book. You might be able to get it from the library.
Karen