I am trying to create - Scolymus maculatus, can someone help please?

What have you tried? Which problem did you encounter?

My initial plan was to model it as-is in Maya, but since I need a large number of these "flower heads," I figured a procedural approach in Houdini might be better. I don’t have much experience with Houdini though, so I’m hoping someone can help.

Anybody?

As Tanto said: what have you tried?

The reason is because with Houdini there is typically many different ways of coming to the same end result.

Without you actaully attempting something within Houdini and posting the file with your attempt; No one can suggest anything.

If you are too new with Houdini to do that - your best bet is to go through the tutorial section and look for something that appears that it may help towards your goal; at the very least you will learn something in parts of those tutorials that could be applied to your project.