What can you do with collard greens?
Collard greens can be cooked and frozen as is and they will keep for months. I cook them in a pot of boiling water and cut them up into shreds after they are done. Pack in freezer bags or cartons. When I use them I defrost a bit and lightly grease a frying pan and fry them with a little minced garlic and a little bit of chili flakes.
Freezing them will be fine, I do it all the time.