Check out this fascinating article on Patterns in Illustrator on Peach Pit Press. It looks like it’s from a series called Mastering Vector Design. The article will teach you how to:

• Apply pattern fills to strokes
• Rescale a pattern within a shape
• Move a pattern within a shape
• Stack multiple patterns in a single shape

Even if you already know how to do some of this stuff, the tutorials are bound to teach you something you didn’t already know, be it a quick key, or hidden menu. Here’s a pattern that I recently created for a friend/client’s interior design agency, Donahue Paye: