To answer the topic question:
150 or 160 is the base score to see WWW, which means you'll see about half of them. You need at least half the base to see a forageable (so 75-80) and only see about 25% of them. At double the base, you see all of a forageable. More details here:
http://ringofbrodgar.com/wiki/Foraging.
Conclusion: you'll need 150-160 to see "lots", and about 300-320 to see all.
Opinions expressed in this statement are the authors alone and in no way reflect on the game development values of the actual developers.