Have you seen A Season of Flowers on shelves? This is a beautiful book for little ones as it goes through the four seasons and poetically describes snowdrops, crocuses, tulips, dogwood, irises, lupins and roses, to name a handful. The illustrations are very nicely detailed, which is important when it comes to flowers since you want children to be able to recognize the illustrated flowers outside. I also really like how big the flowers are on each page!
Enjoy!