Hi, Audrey!
Mother's Day this year is on Sunday, May 13, which coincides with the beautiful
Flower and Garden Festival at Epcot. That's really the only major event taking place during the time of your visit (Star Wars Weekends begins on May 18, 2012 at Disney's Hollywood Studios).
Due to the popularity of the Festival, I'd encourage you to put your Epcot day on a weekday. That will minimize, to some degree, the crowd levels, as weekend visitation tends to tick up significantly.
If you are in Thursday-Sunday, I would suggest Magic Kingdom on Thursday, Epcot on Friday, Animal Kingdom on Saturday, and Disney's Hollywood Studios on Mother's Day. That seems to give you the most Park time while keeping you away from the typical crowd flow pattern.
On Mother's Day, many of the restaurants offer special brunches. Give the Disney foodies a call at (407) WDW-DINE to see what's happening at Hollywood Studios that day; alternately, try to get a reservation at one of the gorgeous Resorts that are catering to moms on that special day.
Have a wonderful time!
See you later, celebrator,
-Deborah B.