The trivets my mom and grandma had were usually made out of wood or metal and they are decorative and flat. You use them to set hot dishes on when you set food on the table. My mom tends to use hot pads any more instead of a trivet.
We even made one out of popsicle sticks in Bible School when I was a kid.
When I made my first kaleidoscopes for hotpads I thought they were too big for a hot pad so I decided to call them trivets. My daughter borrowed my kaleidoscope trivets for a dinner she gave one time. They just add a touch of color to your dinner table like for Thanksgiving or just your hubby and you. And they protect your table from hot dishes.