Software Engineer business casual shirts?

Hi, so recently I landed a job as a software engineer and they told me that the dress code was business casual. I've read all about it and the general concept is slacks/khakis, a button-up shirt, belt and dress shoes.

My big questions is, in your career as a software engineer, or similar, is it okay to wear shirts with patterns on them? I simply dislike plain color shirts. I feel as if they were too formal or something.

Simple question, but I'd like feedback so that I can start buying clothing.

Thanks!

edit

Thanks guys. That's actually a great idea. I bought a couple of slacks/shirts for work, and will wait to see what people around the office wear before buying more.