Need help with a navigation button/search url

I'm trying to add button to my navigation bar. The purpose of the button will be to show users the latests posts throughout the whole board at that point in time. So a member will click on the button and it basically shows them a search result of all the latest posts across the board for that point in time.

The problem is I don't know a url to use for the button link. I could use the url for "Posts since last visit" but that would not show results from that instant. Is there a specific url/search url that I could use that would show the latest posts?