I have a lot of easy-ish jazzy books such as Wedgwood's easier books (Upgrade 0-1, Really Easy Jazzin' About, Easy Jazzin' About) plus Martha Mier's Jazz, Rags and Blues books 1-4, although book 1 is preparatory to grade 1. Plus most of the standard tutor books. Also ABRSM easier series - Dunhill and Swinstead is probably one of the easiest there. And Piano Party (?) and Piano Party on Holiday?? (AB Bullard??? Not sure as I've lent them both out!!) And Piano Time Jazz 1 (and 2 - although book 2 is nearer grade 2), Sppoky Piano Time and Prehistoric Piano Time, plus the 2 Piano Time Classics books, plus various duet books of varying degrees of difficulty. Not forgetting of course, all the tutor books that I had when I was learning, which although more dated, and I don't tend to use them as series with my pupils, I still lend out when there's a particularly good or useful tune in them.

Hope that's some help! I've been teaching for going on 20 years so it's taken me a while to build all that up, but I've also got a fair few books sitting on my shelf that I rarely use.......

Maybe I should sell them off to free up some shelf space!!
Having said all that, my only beginner adult pupil is not quite at the stage of using the above books yet, but will be very soon. And in fact I didn't use Barratt with her, she's on the Piano Adventures Adult book, as an experiment as I wanted to try it on someone!!!! And it's good - I would probably recommend it more for an adult who has practically no prior knowledge of music whatsoever, whereas the Barratt book moves quite fast...