Dear Gargoyle, there are two schools of thought on egg yolks solo or with the white in mayonnaise. There are online recipes from both schools. It is all in the proportions and length of processing (or whisking).

Here is one which is titled Whole Egg Mayonnaise:

http://allrecipes.com/recipe/whole-egg-mayonnaise

And here is another. The yolk tends to make the product creamier.

http://kristyleigh.com/fool-proof-whole-egg-mayonnaise/#.U4TG200U_cs