After blanching them for 10-20 seconds each, I cut out the thickest part of the stalks.
While I did not follow a recipe, I did some googling for advice on how to best roll these. The answer was one I would not have thought of on my own: use TWO collards per roll and overlap them!
Then I wanted to get rid of a half cucumber I had laying around, so I peeled it and sliced it and threw it in. Fold in the sides first, and then roll just like you would a spring roll or burrito, making sure to tuck in the filling as you go so that the roll ends up nice and tight.