Hello there!
I’m sorry to hear you are dealing with this. I’ve dealt with the same problems, and it’s stressful! But, there are solutions.
First, we must get down to the reason. Sometimes hens just like the taste of eggs, and other times there is a underlying cause.
What is her diet like? What kind of feed is she on? Does she get extra calcium? How many treats does she get? Has there been any changes to her environment lately? Is she healthy?
Are you sure she is eating them? This may be a unnecessary question, but I have seen lots of chicken owners saying their hens eat their eggs, and it actually turns out a predator is, or the hen is finding somewhere else to lay. Is there any way a rat or snake or something of the like could be eating them? Is she laying somewhere else? Like I said, may be unnecessary, but wanted to check just in case!
Once we make sure there isn’t a underlying problem, we can move on to some solutions to fixing this problem.
One thing you could try is making a small hole on either side of a fresh egg, blowing out the inside contents, and instead fill it with mustard or dish soap. Do this multiple times, and put them in the nest boxes.
At the same time you do that, put some fake eggs also in the nest boxes. You can find them online or at a farm supply store. Golf balls work too.
This way, the hen will realize that every time she tries to eat an egg, there will either be a taste she doesn’t like, or no reward at all. It’s important to note that during this time, you need to collect the real eggs as often as possible!
Another thing you could try is roll-away beatboxes, as I have seen others have mentioned. Some hens don’t like them and won’t lay in them tho, so they don’t always work.
Also, is there any possible way you could seperate her from the flock, until you get this cleared up? Sometimes one chicken will teach the rest of the chickens to eat the eggs, and then you have a big problem on your hands!
First try those tips, and if those don’t work we can move onto some others! I wish you the best. I know this Can be a discouraging problem, but with some patience hopefully we can fix this!