For new customers, Treat.com offers a Mother's Day Card for free via coupon code TRYTREAT. Get free shipping when you choose to have the card sent to your own address, otherwise shipping adds 46 cents. That's tied with our expired mention from four days ago as the best freebie we've seen from Treat.com since Valentine's Day, when it offered a free Valentine's Day card.
For select cities only, cards ordered by May 10 at 2 pm ET are only guaranteed to arrive in time for Mother's Day.

Link: http://www.treat.com/occasions/mothers-day.htm