I’ve seen various recommendations for breaking an egg into the bottom of the hole when you plant out tomatoes. Apparently, this works and increases yield:
It’s just a form of fertilizer, so this isn’t too surprising. I’ve tried this in previous years and it seems to work. Sadly when I did it again this year, the raccoons decided they wanted the eggs and dug up the garden to get them.
So, if you have raccoons, don’t bury eggs – or anything else edible & smelly – in the garden.