Trees - making them is craft the boys can do now - there are weeds that work well for arbors - get them gooey and sprinkle stuff on them - or dunk in a box-
There may still be some of the bare weed sticks in a field near you.
check out youtube for various techniques
I do mostly winter - so the frosted bottle brush trees can found for not a lot of money. I couldn't find any plain versions yet.