First, you can feed the crusts of your peanut butter and jelly sandwich to the real ducks and ducklings of Boston Public Garden, happily living on and around their own island in the Boston Public Garden Lagoon:
Then, of course, you have to ride the swan boats around the lagoon, although I doubt that you'll find any peanut vendors.
I suggest that you do not attempt to actually retrace Mrs. Mallard's path. It's a dangerous trip--that's why she needed the help of Michael and the other police officers.
I do suggest that you eat a huge ice cream cone, however:
Then, keep walking down the path, and soon you'll come upon a wonderful surprise--Mrs. Mallard and all eight ducklings!
They're a little bigger than life-size, and they don't mind at all if you stand on them--
--or even hop on Mrs. Mallard herself for a brief ride: