When you see an image on Pinterest and click on it, you will end up on the website, blog or wherever the image came from. In the case of Delectable Mountain it will take you to Bonnie Hunter's website
http://quiltville.blogspot.com/p/free-patterns.html
She has lots of free patterns there & Delectable Mountain is one of them.
Oops, just went there & looked- her pattern is called Scrappy Mountain Majesties