Second the suggestion re the Feminist Bird Club DMV Chapter! The Tregaron Conservancy also runs free seasonal Saturday morning bird walks led by Sam Krause which are great and super friendly - I don't think Sam's doing them at the moment but pretty sure she's restarting them in May/June. I'm in downtown DC and don't drive but have found you can get to some pretty good spots by Metro and CaBi - I bird regularly at Theodore Roosevelt Island and there's a CaBi bike dock right by the footbridge over to the island. I've also enjoyed good birding at Oak Hill Cemetery, Kenilworth Aquatic Gardens, Hains Point Park, along the Potomac between Fletcher's Cove and the Chain Bridge, and the National Arboretum, all by bike or public transport. There's great info about a bunch of different birding spots around DC here: https://birdersguidemddc.org/explore-birding-sites/by-region/washington-dc-region/