I collect mine on public desert lands around Palm Springs (county lands, not BLM). I find a lot near my friend's house--where people often dump trash, tires, etc. So I'm not too concerned about degrading the already degraded environment there. And I only take some from one area--not all of what I see, leaving the rest for the critters. Lizards, tarantulas, etc like to hide inside, so be careful when you pick it up, and shake it out thoroughly. Tread carefully--cholla country is also rattlesnake country. Used to collect it near another friend's house up near Joshua Tree, until two of his dogs got bitten by a Green Mojave rattler that have much stronger venom and are a lot more aggressive than most rattlers. They nearly died, but $8K in antivenin & ICU bills later they're both alive, though one lost an eye.
Some is newer with the bark still on, and the older stuff is more skeletonized like you see at LFS. But some has been out in the sun so long it's pretty fragile & crumbly, so some with most of the bark gone but not too old is the best stuff to work with. A good soak and spray down with a pressure washer removes any remaining bark, sand, soil, etc. It might float when you first put it in, but it sinks pretty quickly. Java fern loves it.
