This offer is so annoyingly specific that I almost didn't post it, but who knows, maybe someone will find it handy. Hallmark is offering a BOGO deal on their cards today, April 16, as long as both cards cost $3.49. There's also a bunch of fine print, which you can see if you click on the green banner on their homepage.
I think it's intended for you to get a head start on Mother's Day, but honestly, I don't even know when Mother's Day is this year, so I am way behind. Also, I like cards that cost 99 cents, so you don't NEED a coupon, but that's just me.