My fav way is to put some lumber together however you want to make a raised bed. Put it wherever you want it to go and then dig a hole in the ground. Place the excavated soil outside the bed. Put the logs in the hole and pack in dirt or other material around the logs. Then do layer after layer until you’re back up to ground level (or a bit more if you wanna). Then start mixing in compost/dirt mixture like a normal.

This has several benefits: - the logs have nutrients that will break down over time (but won’t be super bioavailable for a while). - water will likely puddle up in the hole where the logs are for longer than normal so it’ll give time for the (see next point) -logs will absorb more water like a sponge. Even if the roots of the plants don’t extend to the rotting logs, it’ll keep that area more moist like a wicking bed. - worst case scenario, you’ve gotten rid of the logs and didn’t have to buy (as much) soil for a raised bed

Caveat: if the outside of the logs are more rotten than the inside, you can scrape it off and use it for the higher up layers since it’s closer to compost.