Don't know about Oakland, but I know for certain that the two Sunday markets in the "Marin Farmers' Market Association" (Marin Civic Center and Newark) will be open and having egg hunts for the little ones.
From their home page http://www.marincountyfarmersmarkets....
"The Marin Farmers Markets will be open on their regular days and times over Easter weekend, March 22nd and 23rd. Come celebrate the arrival of spring and its bounty. Our weekend markets will be hosting the following festivities. Hayward: Egg Hunt 10 AM -12 PM, Oakland Grand Lake: Egg Hunt 12 PM, Newark: Egg Hunt 9 AM - 12 PM, Sunday Civic Center: Egg Hunt 10:30 AM at Pony Hill."
Note that only "Sunday Civic Center" and "Newark" are Sunday markets.