Eric Carle books (our favorites are From Head to Toe - very interactive, The Hungry Caterpillar, Brown Bear series, The Artist who Painted a Blue Horse)
Little Blue Truck by Alice Schertle (and its sequel, Little Blue Truck Leads the Way)
Dear Zoo by Rob Campbell
Big Red Barn by Margaret Wise Brown
The Carrot Seed by Ruth Krauss
The Snowy Day by Erza Jack Keats
Peter's Chair by Erza Jack Keats
Harold and the Purple Crayon by Crockett Johnson (and we do have purple scribblings on our walls... so beware)