Parent and child groups for fun and free offered...
City College has been offering free parent with child "classes" for years in various locations in San Francisco. It's a great and safe place for babies, toddlers, and preschoolers, to learn social skills while having fun! And the parents/caregivers get to make friends in the process as well, in a drop in -stay as long you want- setting, They are called classes, but it's more like a big playgroup, complete with structures, toys, art projects, singing, and snacks.
Check child development programs for parent and infant, parent and child, for times and locations.