Spring has long been one of the loveliest themes in literature. The season means rebirth and rejuvenation; fresh air and sunshine; optimism and possibility; bunnies and flowers. Nowhere is this phenomenon more delightfully manifested than in the realm of children’s books. Here are some book picks to refresh your child’s library this season. ‘Flip, Flap, Fly!’ by Phillis Root (Candlewick Press) For the youngest book lovers, this immensely adorable picture book, illustrated by David Walker, features encouraging moms and adventurous baby animals, along with a plucky and rhythmically satisfying text that bursts with happy curiosity and love. Parents are sure to hear “Again, please” at the conclusion of each reading. ‘Growing Vegetable Soup’ and ‘Planting a Rainbow’ by Lois Elhert (Houghton Mifflin Harcourt) Bright, modern graphics and simple text (great for beginning readers) bring to light the fun celebrations of gardening and harvesting. Descriptive secondary labels accompany the bold graphics, …