Creamy Tan Until I'm Older

It may not appear so from my blog, but I haven't actually had very many conversations with my children about race.  Partly because I haven't really figured out what to say, as evidenced by this conversation I had with SnapDragon 5 months ago.

The books say children don't connect skin color with race until age 4-6 and that children under 6 will often answer the question of their color or another's color with the color of their shirt.

Me:  What color are you?
SnapDragon:  What do you mean?
Me:  What color is your skin?
SnapDragon (looking at his arm pensively): a creamy tan

SnapDragon was six.  The books also say that until about age six they don't know skin color is permanent that perhaps is changes with age like height and hair color.

Me:  Do you think you'll always be creamy tan?
SnapDragon:  No.  I think I'll be darker when I grow up.
Me: Darker, how?  Like the people at the next table?  (They were Latino)
SnapDragon:  Darker like you.  (I think I'm about the same color as SnapDragon).
Me:  What about Sunflower?
SnapDragon:  I don't know.  I don't know what color she wants to be when she grows up.  Maybe darker like you and me. (I think she is already darker than I with her tan Sicilian skin, but who am I to correct the artist in the family?)

This first conversation with SnapDragon clearly did nothing to further his understanding about skin color and race.  I didn't even correct his odd misconceptions because I didn't know how.  I didn't want to take away his innocence or force him to start seeing race and perhaps take away the wrong message from it.  Yet the books say that not talking about race is in itself an aspect of white privilege.  However, I do want him to learn about race and racism from me and my husband, so we'd better read some more books and start talking.  What book would you suggest?