HELP! Products in a book?

[GlueSticksEverywhere]

Can anyone tell me what happens about this? I am writing a children's picture book and would like to mention a product (it's a food but a brand food) possibly also with an image of it although that is flexible. Do rights need to be agreed just to mention it or only if I picture it (not a photo, rather an illustration).
Thanks!

I don't know, but I suspect a good rule of thumb is not to mention brand names. Not just for rights reasons but also because it can be construed as advertising to children. Try making up a likely-sounding alternative instead - so instead of Coco Pops, call them Chocco Crackles or something like that.