Goldilocks's Pallet Wood Planter Project

First of all, I have to say that Dear Wife is the love of my life. She is never wrong. I guess sometimes I don't hear too well, or maybe just have not read her mind correctly. It's entirely my fault that some details need to be refined before I get it right.
The other day, Dear Wife asked me if I could make some pallet wood planters to put on top of the tree rounds that she has out in her wildflower garden. She has been putting a plastic pot on top of each round for a number of years, but now she wants to get rid of the plastic pots and put wooden planters out there. The rounds are in groups of three, and each round is at a different level - low, medium, and high.
She has three groups of three rounds like that out in her flower garden. So, I ask her if she wants to put a planter on each round instead of the plastic pots. Yes, she says. OK. I go outside and measure the rounds and think an 8X8 inch planter would be a good size to put on each round. Maybe a little bigger, or even maybe smaller.
I go back into the house and show her how big an 8X8 inch planter box would be. Fine, that looks good to her. Yesterday, I built a quick 8X8 inch planter out of pallet planks, used brad nails to slap it together, and showed her how it looked on the tree round. I'm thinking I will probably build another 8 of those planters, more or less that size.
Here is a picture of that planter. It's looks all cattywampus in this picture due to the angle of the camera, but I assure you that it is built square.
And if you are wondering, everything is indeed dry and dead in that picture. We had snow on the ground just a week ago, so springtime growth has yet to arrive where I live.

Anyways, I show the planter to Dear Wife and, much to my surprise, she exclaims that it is way too small! Contrary to what I remember hearing or showing her how big an 8X8 planter would be, what she wanted was one large planter to sit on each group of three rounds.
Well, that changes everything, doesn't it? So, I took her outside and made her explain to me what she had in mind. Mind you, a group of three rounds makes more of a triangle than a square. But she wants one big square planter to span all three rounds. Fine by me, but I tell her that we will have to level the rounds to the same height so that the planter box does not slide off.
After taking some measurements, she decided that she wants a 20X24 inch square planter.

I don't know how you can go from an 8X8 inch planter to a 20X24 inch planter on the same project. I suspect she may have changed her mind, but, for now, I guess I failed to understand her instructions.
Today, I put together a 20X24 inch planter and had it ready for her inspection and approval before I make the other two planters. Turns out, that 20X24 inch planter was too big, so now she wants one that is 18X22 inches. It really is a Goldilocks's planter project with the first attempt too small, the second planter was too big, so maybe my third try will be just right.
I'll have to find a good use for the other planters. It's just not worth my time to take them apart. Maybe they will be perfect for something else.

Actually, it's not a big deal for me to make some pallet wood planters and then finding out they are not the correct size. That's one of the things I like about using free pallet wood. No crying over a project that does not turn out exactly the way you wanted. Just build a new one with some modifications until you get it right.
I'll try to put together a 18X22 inch pallet wood planter tomorrow and see how that works for her. I'm not quite certain why she wants such large square planters, but maybe it's a great idea that I cannot yet see. In any case, it's her wildflower garden and if the pallet planters don't work out, we can try something else.

I don't mind. Pictures to follow when I get the correct sized planters built and put into the garden.