These are also the first scratch and sniff stamps issued by the USPS.
I used some of them on envelopes 925 and 928 sent out for one of Jean's envelope exchanges.
This is not one of the envelopes, and unfortunately the scanner was malfunctioning a bit, hence the grey lines.
I also used some on this envelope and minimal mail art to MomKat in Greece. I called this one 'Is it pink, or is it lime?'
For more fabulous F posts, head over to the links at Sunday Stamps.