The bed is going to be 16"x3'x32' and against a chainlink fence, so access from only one side. This bed should be permanent. Even if veggies don't work here, or I'm bad at it, I can fall back on flowers, which I'm good at. So don't really want a temporary or haphazard solution to building materials.
Crossties are a sturdy option, 2 tall. The bed would require 18+/- ties. I could step/sit on the edge without worries. They'd last practically forever.
Unmortored cinderblock walls 2 blocks high might work. I could plant in the holes which seems gleefully efficient. But the whole thing might shift without mortor or a significant outlay of rebar in every hole. I'm not a mason, but a fair passing carpenter. Durable long after I'm gone.
Pressure Treated 2"x8" could be built 2 tall as well and sturdy depending on connecting the butt joints and corners. Fairly durable.
Untreated green 1"x8" or 1"x6" pine would be cheaper, wouldn't last as long as the three options above, and I don't see sitting/stepping on the edges. Would take up a significantly smaller footprint. But not durable in the long view.
I usually use pressure treated because I don't want to have to replace it as often. I'm sure someone will share the evils of using pressure treated wood, but an objective study will show the risk is minimal. Its your decision. Whatever makes you comfortable
Would like info on planting and growing "Creasy" in the Southwest. Will it grow in the El Paso, TX. area where I am now located. I'm originally from the Mountains of Virginia where it grew wild and we enjoyed it immensly
Etnredclay, You might check out the fake landscape timbers. I built a 4x16 raised bed for a daycare that looked nice and worked good . The lumber yards will have butt connectors and corner connectors for 1"and 2" boards. Hope this helps. Fred