I don't know about collards, but I make a yummy cabbage soup . . . actually I just picked up the ingredients to make it.
Amounts vary, depending on taste and how much soup you want to make. Sorry, this isn't exact, but I don't have a recipe. I just wing it.
Salt & Pepper
Onion (cut into quarters and thinly sliced)
Sliced Polish sausage (pre-cooked -- fried a bit to crisp up the skin if preferred)
Cabbage -- sliced thin or whatever bite-sized pieces that you like
Clean and cube red potatoes to bite-sized pieces (or you can use the baby potatoes cut in half) I usually leave the peel on. Wash and rinse thoroughly until water is clean. This is important because you will be using the potato water.
You will need a pot big enough so that the potatoes and water fill the pot only about 1/2 way.
Cover the potatoes with water (about 2 inches over the potatoes) add bay leaf, salt & pepper to taste (I like more pepper in this soup) and boil uncovered 'till about 1/2-way done (about 1/2 hour).
When the potatoes are 1/2-way done add the onion, carrots, garlic and polish sausage.
Continue to boil for another 15 minutes until carrots are al dente.
Remove the bay leaf and add vegetable broth until the pot is filled about 2/3 to the top. Bring to a boil then turn down the heat.
Add the cabbage a couple of handsfull at a time, gently mixing it in with the rest of the ingredients with each addition. Then when it looks like your pot is about to overflow, cover and simmer for about 15 minutes. The cabbage will wilt down quite a bit so you can add more cabbage to fill the pot again if you like a bit of crunch/varied texture.
Simmer until the cabbage is done to your liking.
Serve with a dollop of horseradish and your favorite hardy bread.