Low Honey Locust Bowl (bottom)

Some fast-growing stuff if it's making 16" in 25 years or so. Reminds me of black ash in the look of it, though, of course, much harder.

Have to ask, why the interior hold? Though for a looker it wouldn't mean much, for a user it would seem inconvenient if not altogether unhygenic. A style thing you originated or emulated?

I need to piont out (just in case you didn't notice) that this is the bottom view.
The recess is not so deep that it would be difficult to clean, in my opinion and experience.
At first, I just liked the look... Made pieces look more "finished" to me. While it takes more time, it is "just a detail," pretty much the same as on a rim, in my mind... I also used the inner detail to help define the foot for the viewer, without lifting the piece up and turning it over.
The Ash piece I just posted is another example. Many of my closed form pieces have that detail as well.

THEN I was introduced to the work of Robert M. Hamada, an elderly, lifelong wood turner in Hawaii. For him the recess seems like a signature, a sign of care for details.
A hard square edge is difficult to get well finished, it takes a lot of attention to the process. So, in that respect, I adopted his reasoning and logic for doing what I already found attractive.
Most of the pieces I make are more for decoration, but like this one, could certainly be used for food service. I would prefer that soup or stew not be served in it, but that has been done for centuries too.
We have used a great old hand carved Hawaiian Hau wood bowl with cracks and a chip for YEARS without any health problems or concerns.