There are many things that can be eating them, the pattern of the damage can provide clues, so post some photos. You should also look closely at the plants to see if there are pests hiding in the plant or around it. Hard to recommend a solution without knowing the problem. Could be slugs, snails, earwigs, caterpillars (cabbage worms), leaf cutter bees.

For starter diatomaceous earth is good for deterring the many of the pests, I switch to using more of it lately to deter caterpillars and whiteflies with pretty good results. It's cheaper than spraying to me and put less stress on the plants. Neem oil is an organic spray that many gardeners use, although most neem oil sold in hardware stores are junk and not effective. The spray I use is cold pressed neem oil with Dr. Bronner's peppermint soap. You could make your own with juiced pepper and garlic, but it can be very strong and burn the leaves if not diluted properly. For now diatomaceous earth is my favorite pest control, but it can be messy and can harm pollinating insects if applied on flowering plants. The rain washes it from the leaves too, but it remains under the leaves, which is where the pests mainly hides at.

Thanks! Actually after I posted this I finally caught the little critter(s). Some kind of caterpillar, but it didn't look as green as I thought cabbage loopers are. Very small. Saw one and manually removed it and ordered diatomaceous earth on amazon. Came out the next day to apply it when it was delivered and there were DOZENS. They have/had taken over the collards. Hopefully the diatomaceous earth will eradicate them soon so they can get back to growing.

There is a product called BT that is the best at ridding veggies of caterpillars. The product I use is Bonide Thuricide. This particular product does not say it is organic but I am sure there a many BT products that are organic.

Just thought I would update in case anyone had similar problems. I spent a few days heavily removing the caterpillars manually and making sure that area around stems and underside of leaves had plenty of the DE and they cleared up. Three of the collards survived and look beautiful now, although stunted, but hopefully will pick up again after the weather warms slightly.