Here is a sample list of things we had to find:
5 white rock
2 different green leaves
wood from a fallen tree for the fire
10 pieces of trash (throw them away)
If you live or visit the sea you could include:
If you are in your yard:
10 weeds (free gardening for you!)
For things that are hard to bring back or pick up have them take pictures of or draw:
an animals home
2 different animal tracks
If you have younger children who can't read yet or are learning; make your list a picture list. That way they can participate too!
You are the parent let them have fun, but keep them safe. You know what is around your area, so pick items that will keep them at a safe distance for you. Give them boundaries if needs be.