Relatively clean two-dimensional data for an example classification?

Question

So, I've been searching around for a dataset to use in an example about Decision Trees. I was hoping for a two-feature, two-or-three classification problem so as to keep it as simple as possible to explain and to visualize. However, I'm not able to find even clean-ish datasets that separate well in only two features. Does anyone know of any such examples, even if they're somewhat unrealistic?

Few other restrictions:

• No image classification - I'm focusing on a mathematical angle in the example and images would lean a bit too heavily on the computational aspect.
• Simplistic or well-known - Niche datasets about a specific field don't really make sense, but if they fit the requirements well I'll be happy with them.
• Region doesn't really matter to me, although if relevant I would tend towards datasets about European countries
• Ideally looking for free datasets
• Format doesn't matter

Thank you so much for your help!

Answer 1

The Iris dataset is well-known, and I've experimented and found that using Petal length and petal width as features makes for a very good example.