Starbucks coffee grounds. No, they won't acidify the soil. The acid goes into the beverage. The grounds are neutral.

See if a deciduous tree is dropping leaves in the neighborhood and ask the homeowner if you can rake and take. Let them get good and crunchy-dry and stomp them into an oatmeal texture. Good stuff.

Here's a couple of links that come quickly to mind:
* Free wood chips
* Free mulch

Thanks for the tips! I have "reserved" starbucks coffee grounds. My ph is too high, so if some acid leeches into the soil, all the better.
I have a liquid amber, so I spent sometime picking those nasty little balls out of the leaf pile and crunching the rest.
I have used the free mulch from the city in the past, but it had broken glass, and I think that was how I got a horrible grub infestation.
I work near griffith park equestrian center, do you think I should ask for horse poop?

Horse poop is fine if it has been composted first, which means you need to let it set for a while before adding it to your beds. Otherwise it can "burn" the plants.
Grubs don't come from glass, of course, but you never know what's in the free city mulch if it's ground up from things people put in their green bins. It can contain diseased plant materials and all sorts of other things.

HA! I just reread my post, and it does read as if I was accusing the glass of causing grubs. Sorry about that, I meant I got grubs and glass, (and who knows what else) from the city.
Thanks for the horse poop advice, how long should it set?
K

Free is free, and perception is reality, so you can pick and choose whatever risks you are comfortable with.

The free muni-mulch will have bits of plastic, glass, and rocks in there. I'm able to sift through the mulch a bit and pick those things out before applying it. You don't have to blindly apply anything. Is commercial mulch guaranteed not to contain diseased plant parts when the label contains, "Forest By Products" and other nebulous things? And what plant diseases are we talking about? Ubiquitous wind blown organisms like powdery mildew? The garden is not a sterile environment.

As for grubs, the green fruit beetle grubs will burrow into any areas with decaying OM. I get a lot in my compost bins where minu-mulch hasn't been. These grubs are everywhere in the Valley. They don't harm living plants, they won't bite you, and smash up with a stomp.

Horse manure tends to be weedy unless composted at high temps, and will contain salts from the urine. And hopefully you won't be hauling it in your back seat. :)