This page of the collecting guide will be the single most useful to those who don't have the Collection Helper Lifetime Reward. Here you'll find helpful screenshots of my Sim using the collection helper in both Sunset Valley and Riverview. Note that there is no distinction between, for example, beetles and butterflies on the maps for insects. Likewise, the maps for Rocks, Gems and Metals are non-specific. Find good locations and take note of them, and you'll gradually find some favorite spots to hit up every day to find the rarest gems.
I did not cover every square inch of ground, but this is plenty of data to collect every item in the game. Look for the insect or gem icons on the maps for locations. They generally respawn once a day.
