Here is something I used to good effect in the past, free sample paint cards. I got a whole batch of these from B&Q's once, then I spent sometime cutting them down and then placed them all into a small container.
This idea was given to me by a friend, she was telling me that she uses where she works in a kinder garden, so I thought I would give it a go. I went out with one of the boys I use to work with for a nature walk.
I asked him to pick one of the cards from the container and I picked on as well. The aim was to try and find the colour we had just chosen in nature, once we had found it, we would either talk about how that felt, for example did it remind us of anything, what happened on the journey to finding that colour? Did we see any animals, birds or any interesting looking plants.
We played this game for hours before heading back to the school when we found a real deep orange in some rotten wood on the way back, we had given up on this colour earlier believing that we would not find it at all, because we had spent ages looking for it and could not find it anywhere.
Funny how things turn.
I am now using this as part of my Natural Awareness course where I can take it to a much deeper level, but what a great game for just having fun with kids and so cheap as well.
Try it, let me now how you get on.