"Leather Seam" Brush?

This is probably an extremely basic and simple question, however, while working in Illustrator I noticed that while trying to use the brush tool, instead of drawing a simple line, it's using the Leather Seam pattern? I'm extremely new to Illustrator, as in this is the first time I've opened it, but I tried to find how to rid of it, but nothing seems to show up. Sorry for asking what is probably a ridiculous question, but it's really frustrating. Here's a screenshot of what is happening, if that helps.