Yes, I use collected wood.
To make aquarium safe, I suggest:
1. Collect hardwood only, preferable ones that had been seasoned for at least a year. <Otherwise, you would have to do the seasoning yourself & it will take months.>
2. Collect from non-polluted areas - stay away from farms in case of pesticide residue.
3. Remove all rotting parts with saws, chisels, etc. Wash thoroughly, scrub with wire brush to remove all loose debris. <You can do the prelim cleaning with a high pressure washer ... saves lots of scrubbing.>
4. Disinfect & water log the wood. If the wood is small enough, you can boil the piece for 1/2 hr or so. For bigger pieces, pour boiling water over the wood & soak it in the hot water.
5. Sink the wood in a barrel of water (put some rocks on top of it) until it is water-logged & will remain submerged on its own. Change the water from time to time to remove tannins that leech out from the wood. Keep soaking until the wood is water logged & the soak water is clear enough for you. tannins are not dangerous, but some don't like the tea colored water in your tank. So it is best to get rid of most of the tannins while the wood soaks in the barrel. How long this will take depends on the wood. Seasoned wood will take much shorter (few weeks), others might take a year or more. I try to collect wood from the bottom of a lake or river, so the wood already is water-logged & tannin depleted.