Building garden structures with available wood

 Hoo-boy!  Look what my friends are giving me, if I can get it to my house.

I want to use it to make the retaining walls that I thought I'd have to wait for, to purchase cement blocks for.  I know they'd decompose in 3+ years, but maybe I could do something cheap to preserve them longer.  Like scorch and wipe with boiled linseed oil.

But how can I make a good solid structure?  I used some foam bits and bobs to get ideas.

A major problem is, transporting the wood rounds to our place.  They're flipping heavy!  Like 400 pounds for the biggest pieces.  I have a friend who has a heavy duty trailer, and he says he can transport them in 6 to 8 trips.  He also has a 32" chainsaw to bring the size/weight down, but I want to keep a lot of them whole.  He also says we'd need to rent a trackhoe to get the pieces loaded onto the trailer, and even then, you'd need 3 people to maneuver the pieces into the trackhoe bucket.

Gawd!  Free wood is not free.  I wish I could wait until the pieces dry out, but my friends want them gone before spring.  So, I need to make decisions now, for the cuts.

Hooo!  I'd love to make a fence using the discs, upright.  I wonder if there are enough.  I'd need 300 feet times 2, and 150 feet.