While there are plenty of websites, books and other resources about #kidlit, here are some that I found especially helpful (and continue to do so) in my own life as a picture book author.
Memberships and Courses
SCBWI: Whether you are an aspiring author or have several published books, an SCBWI membership is equally valuable. From free virtual events to paid conferences, this is a gold mine for children's authors.
Children's Book Academy: The annual writing course is by far the best picture book writing course I've taken. You can have unparalleled access to Dr. Mira Reisberg and an amazing faculty of editors and agents.
12x12: A fabulous membership-based community encouraging writers to pen down one picture book a month.
Highlights Foundation: A plethora of workshops, in-person and virtual. Plus writing retreats to inspire and nurture your creative self.