I am looking to begin learning the keyless flute. Please give me your suggestions for a keyless flute in the key of D that would be suitable for a beginner. Your input is appreciated in advance. 
Personally I think it would be handy if you say your price range, your material preference (wood/ delrin) and where you are located.
You will get the usual Delrin Copley, Sommers, Burns Folk flute, etc. but your question is rather open ended without criteria?
Do you want a slide for instance?
Do you mind a wait?
These are the types of questions you should think about.
All the best,'Patrick
A little ways down the page you’ll find this thread, which pretty much addresses your question.
I started off with an Olwell bamboo in D, then went to a Burns folk flute, and now play a Copley all-wood 3-piece flute. I’d recommend the Copley or Burns without hesitation (although the Olwell was a great flute for having a cylindrical body).
Interestingly there is one of each being offered on the Used Instruments Exchange Forum at this very moment. (Neither by me.)
Best wishes.
Steve