Smallville is in... Kansas?! [Kansas DLC]

but apparently, the Kent family farm seems to be a little easter egg that the devs have slipped into the Kansas DLC.

The Kent Farm can be found off Highway 50, somewhere in the middle between Dodge City and Hutchinson.

As the roads are not shown on the map, you'll have to keep an eye out for the two junctions leading to the area. Here's a close up of the area:

When travelling east, from Dodge City to Hutchinson, the junction labelled A would look like this:

When travelling west, from Hutchinson to Dodge City, the junction labelled B would look like this:

After moving further in, away from the highway, you'll eventually reach the Kent Farm.
You may enter from either of the two entrances to the farm, but if you want to see the main entrance with the sign, it's at the western road leading in.

Have a look around, and you might even catch sight of Superman's suit hanging out to dry!