I assume you are already putting some or all of the egg shell in with your plants.
I looked around and using egg yolk as a fertilizer has several issues. If you have an outdoor compost pile you could add them to that, but mixing large amounts of animal protein in a compost pile can be problematic, so I would use caution depending on how much plant organics you are adding to the compost pile.
Eco-Cycle recommends that whole eggs not be composted, although eggshells can be composted (eggshells are high in calcium and good for the soil). There are three reasons for this recommendation.
Whole eggs tend to attract unwanted attention from animals such as mice, skunks, buzzards, and bears. Biting insects may also lay eggs in compost that contains whole eggs, leading to more flies and more bites.
The bacteria that do most of the work in a compost pile are aerobic bacteria, which require oxygen to digest waste. These bacteria oxidize carbon compounds and generate heat as a by-product of their growth and reproduction. This heat accelerates the activity of other bacteria, speeding the breakdown of materials in a compost pile. In contrast, the bacteria that thrive on meat scraps and other high protein sources, such as eggs, are anaerobic. Anaerobic bacteria grow quickly without fresh air. They break down proteins to generate energy, but do not produce much heat.
The by-products from the breakdown of eggs can make a compost pile stink.
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A comment mentions using egg yolks to feed carnivores and/or omnivores. You don't mention any pets in your question, if you have pets you should probably talk to your vet about it.
I found several posts online about feeding eggs to birds. If you are in the habit of feeding the wild birds, adding egg yolk to the wild bird feed seems like a viable option.
Eggs are a powerful food that feeds the brains of these sharp creatures. It takes a certain amount of intelligence to survive in the wild, so a meal from an egg is a good choice. Egg yolks contain choline which is a serious brain food because it makes rapid thinking far easier by speeding up the relay signals in the brain. The choline found in eggs also aid liver function and transferring and distributing nutrients throughout the body where it is needed. Source
