A little bit old, but still a good book for beginner to intermediate -- Programming PHP by Rasmus Lerdorf and Kevin Tatroe (O'Reilly); has some animal on the cover.
Another one that I can recommend that's geared towards PHP5 is Beginning PHP5, Apache, and MySQL Web Development (Programmer to Programmer) by Elizabeth Naramore, Jason Gerner, Yann Le Scouarnec, and Jeremy Stolz (Wrox); red cover with people on top.