Not too long ago I started to receive an endless stream of Google Two-Step Verification codes to my cell phone. I had not changed anything, but I had no way of stopping it and hoped the problem would resolve itself. Well, it turns out that it does not. What you need to do is use Google Authenticator to receive these codes instead of opting to use SMS text messages.
To do this, go to your Account Settings for two step verification and you will see the option to make the switch. Not sure where this is? Log into gmail and click your name in the top right.
Google Authenticator works for both Android and Apple phones.