Originally the feed gadget is used to show headlines or newest article from other sites. And the feed gadget can also be used to show the newest article from your blog (that is, recent posts). So, to add the seemingly unavailable gadget to your blog, go to Dashboard > Layout > Add a Gadget, and choose Feeds. In the feed url, enter http://yourblogname.blogspot.com/feeds/posts/default. So in my case its:
http://blogger-newbies.blogspot.com/feeds/posts/defaultHit Save and position the gadget where you want it to show. Done!