From your suggestions, here is a list of places offering brunch specials (double check this) and things to do too! My mom, mamaw and sister always went to a nursery and bought flowers, so I'm hoping we can do that this year too!
Stillwater-Brunch at Feller
Birches
Boat Cruise at Treasure Island
Make your own candles at Olfactory Scent Studio
Brunch at Parlour Bar
Como Park Conservatory
MN Zoo
Gertens
Ike's
Mousse Sparkling Winery in Jordan
Granite City
Lake Elmo Inn Brunch
Maynard's
Hazelwood in Excelsior
Crave
Al and Alma's Mother's Day Cruise
Stillwater River Cruise
Baldamar in Roseville
Park Tavern
Uptown Bar and Grill in Waverly
Vineyard Day
Farmer's Market
Tavern Grill -Woodbury Brunch
The Block SLP
Tea Service Mad Hatter Anoka
Arboretum
Mini Biscuit Bundle from Hot Hands
Fruit and Grain Baker with Mother's Day Menu for Pickup
Ikes
FoodSmith Pub Brunch