I started my raised beds this year doing a somewhat Hugelkultur method.
I had my son dig a trench a couple feet deep, then mr. mm and I went around the property and picked up all the old rotted logs we could find and tossed them in the trench as compactly as possible. We filled it plus some.
I also threw in some veggie scraps and dead weeds that have started to rot, those actually went in first, in the bottom. Then I shoveled some of the dirt back on top of it. I’m going to place cinder blocks around the edge and then fill it with enough dirt to make it level.
Fall is a good time for your efforts. Lots of people rake their leaves and place them in bags by the curb. Makes it very easy to pick up and scavenge.
Good luck with what you’re doing.
Let me know how it works out.
Just as an aside, as I’ve been repotting my houseplants, I’ve been saving the dirt and using it for my garlic bed. Our soil is unforgiving when it’s dry.
I’ve heard of hugokultur. Unfortunately, neither I nor my husband can dig trenches, and he probably would balk at renting a backhoe. (Wish I could afford to buy him one -— he’d be digging up the whole neighborhood)! And Lord knows we’ve got plenty of tree limbs and wood scraps we could bury!