I really don't know the answer to your question but maybe some one who does will chime in.
I just hope you get to feeling better real soon. flu is bad stuff. Take really good care of your self.
Bonnie

I think oak from a saw mill would last pretty long. I have an old building of oak and someone put cheap siding on it. Termites eat the siding and pine door jams and leave the oak. I also asked for railroad ties for Christmas years ago. I got oak 4 by 4's not what I wanted but they lasted 20 years laying on the ground. I am afraid of those green boards; don't know anything about building raised beds but concerned for your safety.

I wouldn't be afraid of the boards now. Didn't they make them stop using the dangerous stuff a few years ago?

I hope you have some help! I can't imagine handling an 18' 2x8 by myself or even a 2x8 16'.

I agree about the saw mill type oak. We built gates from that kind of wood 30 years ago and it is still sound. Also built some corral type fencing that was exposed and it is still good. Touching the ground might be different though.

Have you considered just the mounded soil type beds with no sides? In other words, the lasagna beds laid out in layers which is pretty square stacked if you have flakes of old bales of hay to use or straw. Just tossing some thoughts out there for you.

Yes, the majority of my raised beds now are mounded, but once I had the block raised beds-till I stole them to spread out over more beds--and there is nothing like being able to sit on the edges of the beds to garden. I figure a extra board between each of the beds will make a excellent portable seat. And, I do find sitting on concrete for awhile isnt too pleasant. I would probably try oak planks-and there IS a lot of sawmills in our area-but I asked once, and they sell on contract-well out of this area.
specalized like Dr's, I guess.
I'm hoping me and my trusty Cub Cadet can get the boards to where I can handle them-hate to admit to age limitations yet, butI do notice it more and more.
On the green oak? Dad built a shed 60+ years ago, not a speck of rot when they tore it down last year. I do think this second, and third growth timber isn't as solid, somehow.

A neighbor used to have a small saw mill and I used to get scrapes for kindling. Some were fairly long but only one inch thick. I had to cut them to fit in the stove. It is closed now. I asked for saw dust at a big one near me and didn't get anywhere. Like you said they have a market for it; no time to talk to me. I'll bet a small operation would be easier to deal with. Also some people won't give you the time of day; others will bend over backwards to please.

Seems people are more independent anymore, arent they, Helen. Used to be sawmills in your area wanted your business, and talked nice, now, you're lucky if they talk to you at all.
BTW, I checked with Meek Lumber this morning, 2"X8X16 treated board is $12.06, same in cedar is $45.99