The Legacy Forms group (visible after you click the Legacy Tools icon) includes three types of form fields you can insert in a document: text, check box, and pull-down. Instead, you need to click the Legacy Tools icon, which displays a whole group of controls that originate with older versions of Word.
If you display the Developer tab and take a look at the Controls group, you'll notice that there are a bunch of controls available.
If you don't see the Developer tab (it isn't visible on your system), you need to instruct Word to display it. The fields available for use in forms are accessible through the Developer tab of the ribbon.
