recipes are not protected by copyright. Section 102 of the copyright law, title 17, United States Code, states: “In no case does copyright protection for an original work of authorship extend to any idea, procedure, process, system, method of operation, concept, principle, or discovery, regardless of the form in which it is described, explained, illustrated, or embodied in such work.” The Copyright Office website explains that copyright does not cover "ideas or procedures for doing, making, or building things; scientific or technical methods or discoveries; business operations or procedures; mathematical principles; formulas, algorithms; or any other concept, process, or method of operation.
You should get permission to use personal names.
Just to supplement the earlier response, here is the langauge from the US Copyright Office's website that deals specifically with recipes:
Mere listings of ingredients as in recipes, formulas, compounds, or prescriptions are not subject to copyright protection. However, when a recipe or formula is accompanied by substantial literary expression in the form of an explanation or directions, or when there is a combination of recipes, as in a cookbook, there may be a basis for copyright protection.
So you should be aware that you may have (and should seek) copyright protection for your cookbook when published and if your friends' recipes fit the above description you should get their permission as well. In fact, why not take the safe road and get their permission anyway. In light of the purpose of the book, they would likely agree. I would be glad to discuss this with you to give some free guidance.