One of the books I use as reference for my origami flowers is the book written by Hiromi Hayashi called Origami Flowers: Popular Blossoms and Creative Bouquets.
This book includes many different flowers. And all of them are very close to the real thing, you’d be hard pressed to tell them apart if you mixed the two together! Especially if you look at the pansies inside the book!
Some of the diagrams are for the advanced origamist as the author doesn’t include some steps in the folding process that are not obviously apparent to the beginner. But, if you work your way through the book, from simple to more advanced, then you should be able to figure out what needs to be done.
Overall, it is an excellent book that will show you how to fold very natural looking paper flowers!