Yes, Kansas has waterfalls, at least a few. The reality, of course, is that they are rare, vanishingly rare, and nothing compared to what you're getting in Oregon. But hey, IMHO that just makes it more exciting when you find a beautiful one. Below are pictures of the waterfall at Cowley State Fishing lake. Astoundingly, this isn't even mentioned on the on-line info for the park.
You can click these to enlarge. According to the park, this waterfall predates the construction of the lake (which is around the bend). My friend Matt and I spent the day out there last week looking for arrowheads and fossils. We didn't find much in the way of arrowheads (a broken spear point), but there are fossils all over the place.
The scale is a little hard to show in some of these, but the falls are maybe 30 feet tall? I included Matt in this pic to give a little scale.
This was one of my favorite places to go hang out in college (Southwestern is about 30 minutes away). Matt fished this area a lot, but apparently never caught any fish downstream of the lake, probably because they don't survive this fall and they aren't coming up from downstream (a low-water crossing cuts off fish passage).
Other waterfalls in Kansas? Well, I know of a few, but I haven't seen them. I'll have to figure out how to get access (I think they are on private land). In the meantime, I noticed that groundwater seeping out onto roadcuts was freezing during the winter, and I tried to get a picture of one of these frozen mini-waterfalls.