Jetpack does not include a Follow button. Could you look at your list of active plugins, and check if you installed another plugin named “Follow Button for Jetpack”?
http://wordpress.org/extend/plugins/follow-button-for-jetpack/
If so, you can find the button’s HTML code here:
http://plugins.trac.wordpress.org/browser/follow-button-for-jetpack/trunk/follow%20button%20for%20jetpack.php
If you have any questions about this plugin, you’ll want to open a new support thread here:
http://wordpress.org/support/plugin/follow-button-for-jetpack