People watching, singing along with the radio, walking through the nature park....when I lived in the US, we were close to the Snowy Range mountains and I loved to go up to Lake Marie and just sit. Reading, doing puzzles. We don't do this much now, but 2 or 3 times a year, there would be a "technology day" in the area, always free, and it was kind of like a job fair type thing, where different companies would set up stations to advertise their company or their profession. A lot of them would have workshops for kids to build things, like a solor panel powered model windmill, or something soldered together, or a buzz wire game, bath salts, a clock. You could spend the whole day there and come home with a bunch of things your kids made themselves. Here are some pictures:
One year, they got to make rockets out of empty coke bottles and shoot them off with water pressure...that one was fun. I can't find those pictures. But everything was free.
I think this one was an electromagnet? And they also got to make their own bouncy balls one year...they had a chemistry lab section...the kids loved that one.
Another fun thing, free, is Lamb day. In the spring, one of the towns has their own sheep herd, and they are funded by adoptions. They have one day where you can go and adopt a lamb...adopting does cost, but you don't HAVE to adopt one. They have sheep herding displays with their dogs, they have games and quizzes for kids, and if you DO choose to adopt, it's 20 bucks and you can actually get in to pet the lambs. Since my son is obsessed with sheep, we do this every year.
The nice thing is if you adopt, you can come back on certain days and pet the sheep again when there are fewer people, which is nicer for A because of his Autism...it gets overwhelming for him on the one day, but when we come back, it's not as busy and it's more restful. He loves it. And there are a lot of places who do stuff like this...farms that will let you come in for a day and see how they milk cows, or how they sheer sheep, etc. You just have to keep an eye out in the local papers, or websites.