Dear Wife put in a request for another pallet wood planter for her "wild" garden. I finished the building of the project in the morning. Then she came out and told me where she wanted the planter placed. Had to use a small shovel to level off the planter because that garden is planted on a slope. Anyways, here is a picture of the new pallet wood planter in her "wild" garden...
That planter was made to order at 16X16X16 inches. Of course, she does not need 16 inches of topsoil in the planter for her flowers, so I filled the bottom ~10 inches with pallet wood bits and pieces from my cuttings...
Wood is wood, so I don't have a problem using my bits and pieces from pallet wood cut offs to use as a hügelkultur filler. Got rid of more than one 5-gallon bucket full of pallet wood off cuts in that planter. Much better use of those off cuts than just burning them.
I will mix up some chicken run compost and topsoil 1:1 and Dear Wife will use that to top off the planter. I really like the hügelkultur method of adding wood to my planters and raised beds. Of course, every year some of the wood decays and some soil works its way to fill the voids between the wood, so the soil level of the planter needs a top off of fresh compost every year. But I actually consider that a positive thing because the decaying wood feeds the plants from below and the fresh compost on the top feeds the plants from above. In theory, every year that planter should get better.
Not only are pallet wood bits and pieces great for filler, but they will also soak up and retain water in the planter. That wood will act like a giant water battery, releasing the moisture to the plants as needed. The older the wood gets, the more it turns into a sponge like consistency, and it retains even more water. That's a great feature of using wood as opposed to other fillers like concrete, plastics, or broken pieces of pots - all of which I used in years past.

Anyways, Dear Wife was very pleased with her new pallet wood planter that I built. Happy wife, happy life!