Colcannon to the Irish is like Sunday gravy to the Italians.
Every family has their own recipe.
This makes it a great blank slate for your CSA stash. Look at it as potatoes and greens.

This is a base recipe then there will be suggested substitutions which may take it away from traditional colcannon but they will be delicious none the less. The amounts of potatoes and greens are approximate. Use what you have.

6 to 8 medium sized potatoes – yukon gold, red skinned, pinto or white
A leek, using white and light green parts, sliced in half lengthwise then sliced crosswise into half moons
3 to 4 garlic cloves, smashed and minced
Two cups of finely shredded cabbage (about 1/4 head)
One scallion, thinly sliced
6 tablespoons of unsalted butter, divided
Kosher salt
1 and 1/2 cups of whole milk
Freshly ground black pepper

Put potatoes in a large sauce pan and cover with cold water and season with salt. Bring to a boil over medium high heat. Reduce to a simmer and cook until a knife pierces the potato easily. Start checking at about 30 minutes. Drain. Peeling is up to the eater.

In a large saucepan over medium heat, melt 4 tablespoonfuls of butter and add the sliced leeks. Cook until soft, add the garlic and cook until golden. Add half of the sliced cabbage and toss. Simmer for 10 minutes or so until wilted then add the milk. Bring up to a simmer, add the potatoes and the rest of the cabbage. Mash with a potato masher and season to taste with salt and pepper. Top with sliced scallion and the remaining butter.

This is amazing with bacon.

Kale, arugula, swiss chard, spinach or broccoli raab sauteed down for the cabbage (if you have a greens stash in your freezer this is a perfect use for it.)
Carmelized onions in place of the leek.
Roasted sweet potato with any of the above greens and carmelized onions is delicious!
A mix of boiled and mashed kohlrabi, cauliflower or turnip and potatoes would be delicious.
The variations are not traditional but they are tasty and a different way to use your CSA stash.