My children have found shells and butterflies but not pebbles or beetles. I have leveled up in farming and engineering and am currently working on my dam. Any suggestions?

same with me I think you have to get level 2 exploration than you can find it but I'm not sure.

I would look at the other tech levels.

my thought process - they need to explore to find the shells and butterflies therefor they need to explore to find the beetles and shells . . . how can I make them better explore?

You need to solve certain puzzles.

Do the dam

& clear the thorns

Once you finish the dam, I think the pebbles will start showing up.