Eric Carle's website includes printables and pictures from many books
Collage from UK Activity Village
Collage from Artful Parent
Intro to Collage from Playful Learning
Paper Skyscrapers from Deep Space Sparkle
Collage Ideas from EduArt4Kids
Collage from Art Projects for Kids
Collage Process from Meri Cherry Art Studio
Simple Collage Ideas from Artsy Crafty Mom
10 Easy Collage Ideas from First Cry