If in an open field and if you have a flyer, lure them away from the nest and then quickly fly back and grab the eggs. If you can’t do that, grab a tanky dino and lure them with it and quickly grab the egg before they finish devouring it
I was sitting on a flyer on a cliff above the deinos, thought I was safe to wait for my moment to steal their eggs...had the biggest heart attack when one of them decided to climb up the cliff. I accidentally dismounted in shock and fell right into the packs claws, where they shredded me to death. Don't be scared of them, they smell it.