These creosoted timbers came from some high voltage towers. That white insulator is more than 100 years old and similar ones must have fit in those shallow holes.
Western Red Cedar, 4-1/2" thick, 8" and a bit deep, and 4 Meters long. And you can see they're Freeheart; cut without the center pith. No embedded hardware.
The fella that gets lumber and such for me, steered me to em. I'm lucky to have him instead of a Mr. Haney.
I started ripping a 1 X 4-1/2 Inch piece off two of those timbers, so I could get some 7" boards. Four from each timber, needing two of em side by side to keep that big saw steady.
Then I switched to ripping 8" boards, three from each.