I subscribe to the V&A email bulletins, and my last one had what I thought was a terrific idea from the VA Museum of Childhood. Although a recommendation for children, I think it's good as an activity either with them or just for yourself. It involves some time spent outdoors and in, and needs next to no equipment or money.
All it involves is going out for a walk and collecting items which you find interesting, and maybe with a theme, to arrange artistically on your return home. What that will be, is only limited by your own imagination.
Back at home, find a surface which will complement your collection. This could be a tray, or some fabric or paper which will show off your objects to best advantage.
And then have fun experimenting with arranging them. And, when you find your best result, you can take pictures, either from above or at an elevation, so that you have a record of how it worked out. These could be collected in a scrapbook with details of the day you went for your walk, where you went and what you saw and found in addition to the things you chose to take home.
And if you are a crafter, you could then go on to use that picture as an element in making a card, picture or poster.
I'm definitely going to have a go at this. I think it provides a really good reason for going out for a walk, especially now the weather's not so enticing to go out.
Here's the link for full details and instructions: