Be Careful What You Sniff For #1 (Magic Bone) was a huge hit in my classroom this year. One of my George Brown, Class Clown (Super Burp! #1 (George Brown, Class Clown) fans discovered it (same author) and shared it. The series definitely made its rounds in the classroom and was a definite favorite. This is also a fairly new series as the 5th one was released last week.
Two series I have not yet read but am confident they will have baskets in the fall are The Sasquatch Escape (The Imaginary Veterinary) series and Andy Griffith's series The 13-Story Treehouse. They are on my stack to read soon but I have heard from so many people that they are both perfect for 3rd graders, I imagine I'll be adding these as baskets too.