A name from a modern list
Oatmeal is a soft beige gray named after cooked oats. This name and its code, #C9C1B1, come from an open list of color names gathered online. The list gives no older source for the code, and we could not find one either.
The Crayola crayon is lighter
Crayola sells a crayon called Oatmeal. It was one of the new shades in its Colors of Kindness crayons, as the list of Crayola crayon colors on Wikipedia shows. That list gives the crayon as #D9DAD2. It is paler and grayer than the oatmeal on this page, so the two codes do not match.

