As I was surfing Kellogg's website, I came across a couple of coupons that I thought might interest you...
$1 off of 2 boxes of frosted flakes
$0.55 off of 8ct or larger poptarts
Also, Poptarts Sprinklings Club says you will get "a smattering of samples and a variety of values" if you sign up!
*As always, I am not responsible for any misprints by them or me! Click on the links to get the full details.