Yoga is supposed to reduce stress. And just like the activity, the equipment required for doing it can also be had stress free, as it is just the basics. So here's a list of things you would require before setting off for your yoga class.
1. Yoga mat. This is essential because this will allow you to do yoga comfortably. The mat you get should have a good grip so you don't slip; it should be good at absorbing sweat and should be large enough for you to lie on it comfortably.
2. Yoga clothes. You can wear almost anything to the class with just a few precautions. The clothes should not be so tight fitting as to restrict movement, and they should not be so loose that they get in the way of exercising. I prefer wearing cotton as it good at absorbing sweat and keeps the body cool.
3. Carry a pouch to keep your glasses, keys, and earrings -- basically, anything that you have to remove before beginning the exercises.
It really is a good idea to get your own mat no matter your level. You won't want to use communal ones for long I assure you. It's hard to let everything go when you face is smashed into a spot someone's other parts have been. I practiced at home for years on the wood floor or carpet, which is just horrible. Do yourself a favor and spring for the $10-20 mat, you won't be sorry!