Previous Page Visited for Hidden Form Field

[ Moderator note: moved to Fixing WordPress. Please do not use Developing With WordPress for these topics. ]

I have a general contact form that I am using and I want to have a hidden field in it that contains the URL for the previously visited page. This way, when somebody visits the “Product A” page, then clicks the Contact Us link, the form notification I get will let me know which product they were viewing just prior to the form submission.

Although I could find plugins to display previous pages visited, I just would like something that allows me to put the value into a hidden form field.

Any suggestions for me would be appreciated. Thanks!