I was just visiting at A Wrung Sponge, who was writing about what books her boys would be getting at Easter. I give my boys books at Easter too, since neither of them likes jelly beans or chocolate and I have to give them something or else they will be warped. My 3 yr old will be getting A Seed is Sleepy (can't get much more seasonally appropriate than that); I don't know what my 6 yr old will get. There are so many good picture books about gardens and flowers out there (and more just reviewed in the NY Times ), but there's not much for 6 year olds. All I can think of is The Magic School Bus Plants Seeds, which we have already. There are, of course, various Usbourne and DK books about plants and nature, and although informative and attractive, they aren't really the kind of books you hold to your heart.
Goodness, the internet is remarkable. In the last two minutes I have found this cool botany for kids website that has links all over the place. But still no book. Perhaps poetry.
As basket fillers, they are also getting seed packets...and I will make an effort this spring and we will actually take the microscope out, and press flowers, and peer at things with magnifying glasses, and do watercolors/pen and ink drawings of flowers (with their Latin names) etc etc instead of just reading about these things.