Is it true that it is good to put a banana and egg in the hole before

Not if you have a rodent problem in your neighborhood...why not just use a good organic slow-release fertilizer? Seems like a waste of fruit and eggs.

I tried the banana and found if you have any coons around they will dig them up again and again. Doris

That might have been a good idea back before we had quality fertilizers, but with so many all all natural products available it doesn't seem worth attracting rodents and other critters.

You will end up with a lot of unwelcome visitors

Put the crushed egg shells on top of the soil to combat slugs. Any nutrients will wash down into the soil when you water the garden or it rains. I personally don't know anything about banana peals, except it would invite diggers. Put the peals in your compost to help add nutrients to your compost pole.