I am partially satisfied by your question as most of the high DA sites could not get any free organic traffic as according to my knowledge most of the website having high DA gives the quality backlink except few websites which either do not allow for posting or remove the content after the specific time period.
You can search on search engine to find high DA websites providing free organic traffic.
Some of them are given below as:
1. Sites.google.com (Google)
2 www.blogger.com (Blogger)
3 www.wordpress.com (Wordpress)
4 www.soup.io
5 www.myspace.com (Myspace)
6 www.livejournal.com (Livejournal)
7 www.blog.fc2.com
8 www.pen.io
9 www.lycos.com
10 www.wix.com (Wix)