Last year, when I was trying to make one project-a-month from a different craft book, I made M a little treasure bag, like the one in SouleMama's book, Handmade Home. While he definitely liked having his own little bag, he preferred to tote around his little cars and trucks rather than using it to collect outdoor treasures.
This year, things are different. He's rediscovered his Treasure Bag (and calls it by that name, too!), and requests it every time we are headed outdoors. We've had a bit of a soggy, cold, windy winter in our neck of the woods, so there are constantly pine cones, branches, twigs, and more to be collected. It's really so very cool watching him enjoy being outside, discovering nature. And it's even cooler to see him do it with a mama-made bag in tow.