Cottonwood would not be my first, 2nd, third choice, etc choice. But Free is free. Put a good finish on it and it could last for a while. It's heavy with water weight, does not hold sharp detail but ok for most Chainsaw Carved detail. Often has a hollow at least the diameter of a pencil running up the center that can be filled with putty. Smells funny and burns fine when dry.
Cottonwood is a hardwood and used most often for pallets. The center ring can crack in a ring and pop out??? ring shank??
When carving it feels like a homeless women is spitting on you. Not a problem if you already smell homeless. The sawdust does not mix well with drinking water so use a sealed bottle. Other than that. Enjoy the big log.