Forageable items are items which randomly spawn on the ground and may be harvested by simply right-clicking the item and choosing the 'Pick' option. You do not need any special skills or items in order to pick up forageable items from the ground. Some skills boost the chance of coming across certain forageable items. For example the Slug Hunting skill boosts your chances of finding items in the slug group such as Virginia Snail
The world of Salem has a diverse range of biomes - or tile types. Certain biomes are more conducive to finding particular forageables. You cannot expect to find just any item in any type of terrain, after all!
List of all forageables found in Salem: