I thought that Edmure Tully wasn't a knight, but on reading his wiki page for asoiaf.westeros.org, his title is listed as "Ser" and the page is in the category of "Knights". On Edmure Tully's page on gameofthrones.wikia.com, it says
Edmure Tully is a middling knight...
And a Tumblr user mentions that he is a knight.
Yes, these are all unreliable sources, and I admit I struggled to turn up anything more than those three links. And nothing on any of those links has a source confirming that Edmure is a knight. Yet the fact that more than one person believes he is compels me to ask: is there any canon support (or otherwise official confirming material,) for Edmure Tully being a knight? Answers from the show or the books are acceptable.