I’m sure that you all have seen one of these before, but did you know that it is called an escutcheon. It is a decorative plate applied to the surface around a keyhole. They are usually made of metal (brass typically) but can also be wood or another material. The pictures show just a few designs out of many that are available.
Here is a door knob and keyhole escutcheon in the Arts & Crafts style.
Here is a highly decorative brass escutcheon.
Here are several types of keyhole escutcheons.
I have seen escutcheons made out of tortoise shell, ivory and even bone. Do you have an unusual type of escutcheon on any of your furniture?