I started with a google search for "harford county activities" (insert your county or town). Wow! Jackpot! I was surprised at how many things came up, and, BONUS, they were cheap/free and GREEN! Here are some of the things I found, happening in the next week or two:
Family Campfires at Eden Mill Nature Center (presentations by guest speakers and smores!)
Otter Point Creek/Estuary Center offers a FREE "Meet a Critter" and "Buggin' Out" for parents with kids, and tons of other things for a small fee ($4-$10)
The Liriodendron Historical House has a gallery exhibit on a nature artist: "Forever the Land: The Art and Writing of Kate & Russell Lord" On Sundays- FREE.
And later this summer is the Harford County Farm Fair, which we went to last year and it was a blast! It's cheaper than the movies ($7 adults, $3 kids), and where else can you see pig races?
So do a search for your county or town. You may be surprised what fun things are offered nearby.