That wouldn't work either in a situation like this:
The egg could also hit the ground object from the right or left.
I also can't hard-code an angle to check against for each ground object because the egg could hit the ground from multiple angles...
I saw another forum post where someone else found a way to do this by attaching some small sprites around the object and checking if they overlap with another object. If they did, then I could use their position for a rough estimate for where the collision took place.
I'll try this method and see if it works in my case too.