This happened to me today, too! They were all the prequalified offers on the Simplicity/TYP/and AA World Mastercard, all because I used their prequalified system on the citi website. Only three, though XD and they were in black-and-white, since they were only reiterating the offers I saw on-line. They just didn't want me to "forget", or have them "expire".
Shredded them right up, though
Also got another nice Discover IT mailer...that was dutifully shredded as well!
I wish I had your gardening will power!
Wow, forget my earlier post.. In my mailbox was 3 Citi Pre-qual offers. Citi Simplicity, Thank You Preferred, and AAdvantage World Mastercard, each with its own personal Prequalification number to use to accept each offer...weird...