Here’s a set of free repeat patterns. There’s six in total and they’re all diagonal stripes.
Each pattern is seamless and will tile perfectly on all sides. The download contains six Illustrator vector patterns (EPS files) that you can load into Adobe Illustrator or your favorite vector editing program. It also includes six 24 bit transparent PNGs that you can use “as is” or use for Photoshop patterns (Edit->Define Pattern).