Where to go for a picnic? Here are some suggestions (along with where to get food and drink nearby). Say for instance: “6/15 Green Community Garden, on 6th Ave. between 15th and 16th Sts. in the South Slope. This lush patch’s tables and chairs are open to the public Saturday mornings and Thursday and Sunday evenings (though, sadly, the on-site grill is for members only). If you’re bringing six or more, check beforehand to ensure your gathering doesn’t clash with another’s…Perfect Meal: Fresh mozzarella balls marinated with sun-dried tomatoes, handmade bread, olives, and a pasta salad from Eagle Provisions, a small Polish grocery store on 5th Ave. and 18th St. that’s been serving the South Slope since the Thirties.”–Brooklyn Based