Am I ok to just take driftwood from a local creek or just something I find laying around? I've heard of people doing it and it works just fine, but I just want to make sure that a dry piece of cottonwood, pine, aspen, etc would work. All of these trees are plentiful in Colorado so I would have no problem finding some. Because the pieces I find will most likely be dry and float for months, I'll probably silicone a slab of flagstone to the bottom.