Those are definitely not cedar or pine (cedar has a reddish tint to it, along with a distinctive scent, and I'm sure you can recognize pine), so they're not toxic to your snake. That said, the conventional wisdom with regard to ball pythons is that half logs are not secure enough to be good hides for them. The fact that they have large openings makes them unhappy; they'd much prefer something that they can just fit inside, with a single "doorway" just big enough for them to get in and out. That way they can't really be seen when they're inside, thus making them feel safer.