Patterns embedded into brushes? PS!

Is there a way to embed a texture/pattern into a brush within photoshop. It is weird because some of the brushes I have have textures within them that aren't in my patterns.

I just did a test. Made a new brush off of a new pattern and when I save it, delete the pattern, it is gone out of the brush when I restart. Yeah yeah makes sense... but how are these other brushes I have pulled from across the internet doing it?

Thanks in advance guys

Edit: I tried google btw and couldn't find anything on it.