I’m not an expert on area farms/pumpkin patches, but here is my wish list for other outdoor/fall:
The Big Bugs exhibit at the Museum of the Shenandoah looks awesome. (There is even a Groupon! But it expires in like an hour).
https://www.themsv.org/exhibitions/david-rogers-big-bugs
Hiking at Sky Meadows State Park, apparently there is a children’s hike, and there are some cute eateries there too.
Devil's Den at the National Military Park in Gettysburg, PA Reportedly has cool rock scrambling for the little ones and pretty spectacular views and worth the drive.
Locust grove nature center for hiking and playing and learning at the nature center (check to verify it is open)
Renting a campfire space at Belvedere farm
A ropes course and/or zip lining.
https://www.mommynearest.com/edition/washington-dc/article/6-outdoor-adventure-courses-for-kids-in-the-d-c-area
Kayaking at Burke Lake park
Jug Bay Nature Preserve
Things we have done and loved:
-Brookside Gardens in Wheaton, MD
-Mini golf at one of the regional parks - we went to Upton Hill but my kid loved it so much we will be trying others.
-horseback riding
-Huntley Meadows wetland boardwalk