I learned on the Rubank books and did use the Herring 40 progressive etudes book (though I'm not sure this is for true beginners I did enjoy these etudes). When I get home from work I'll find out what book I just bought for my 9 year old daughter. It seemed to have a very logical approach and had supplemental info like illustrations of the parts of a trumpet and how to hold it.
I would have started her on the Rubanks books, but Sam Ash didn't have an elementary method and mine is missing a bunch of pages. Intermediate and advanced are in much better shape. I'm sure my 40 Progressive Etudes book is in good shape as well. It will be interesting to see the notes scrawled by my teachers inside these books.