show feed name next to title in Trending
and allow me to click through to the whole feed

Unfortunately, shared posts can belong to private RSS feeds that users might not want to share.
However, every post includes a link to the website, so you can go there and check if it has an RSS feed you can subscribe to.
We hope this helps.
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matejcik neasi commented
hmmmm, i didn't consider private aggregate feeds.
My immediate usecase for this is two-fold:
One, i want to avoid clicking through to Lifehacker
Two, in case of tumblr posts, the title is usually something like "(no title)" or "Photo" and the name of the tumblr is more informative about the content than the title.so for those usecases, displaying the name of site (instead of name of feed) would be perfectly acceptable.