Collect all 10. Images on Pop-Tarts made with FD & C approved food coloring. Solve the puzzle to reveal mister E flavor. Fully baked & ready to eat! Or heat. Or freeze. Or stack. RSPO - Certified Sustainable Palm Oil Mixed. K Vets & Supporters: Supporting veteran recruitment at Kellogg. Kellogg's Pop-Tarts mystery flavor sweepstakes No Purchase Necessary. Open to legal residents of the fifty (50) United States and District of Columbia who are 16 years of age or older at time of entry and are a registered member of the Kellogg's Family Rewards program. You must be a registered member of the Kellogg's family Rewards program in order to enter. To become a registered member of the KFR program, go to www.KFR.com/PTmysteryflavor and follow the instructions to complete the registration. To enter, beginning 5/27/21 at 12:00:00 AM (ET) through 8/31/21 at 11:59:59 PM (ET), go to the website and follow the online instructions to register and complete your entry. Subject to complete Official Rules at www.KFR.com/PTmysteryflavor. Odds of winning depend on total number of eligible entries received during the Promotion Period. Void where prohibited. Sponsor: Kellogg Company, One Kellogg Square, Battle Creek, MI 49016.