I found my driftwood at a local river. If you can get to a local lake or river you should be able to find some nice driftwood. You are going to want to look for DEAD wood. Not freshly cut green wood. Green wood will leach sap and other toxins into your water. Look for some nice weathered wood that does not have any bark left on it. If it does have bark you can always remove it, but it is not recommended to put wood with the bark still on it in your tank. After you find the wood you want you need to clean it up a bit. I scrubbed mine with a brush, washed it in the dish washer, soaked it in bleach water, and rinsed it hot water. This worked very well for me. Have not had any issues with tannis or mold.
Check out my driftwood thread.
And good wood hunting to you.
I found my drift wood on my local beach. It was very sun bleached and who knows how long it was floating in the ocean, anyway the more sun bleached it is the less it will leach.