The shores of Lake Merritt are a party every day of the summer, but one day is always particularly loud. That’s the day of the annual Eastlake Music Festival, which will take place again this Saturday, May 28, from 1 p.m. to 9 p.m. at the south end of the lake and the Henry J. Kaiser Conventions Parking Lot. The free fest features its own miniature circus of food trucks and pop-up stands from local businesses. Plus, right in front of the lake, two stages with full music and dance lineups. This year, that includes local psych-surf band Eyes on the Shore, Santa Clara alt-rockers Picture Atlantic, funk outfit Sal’s Greenhouse, and Berkeley’s Bear Lincoln. But, really, it doesn’t matter much whose playing when you’re sitting on the grass in the sun.