In general, the formula for determining how many turns it will take to find an item is:
Turns = 200 - (3 * Foraging Skill)
This is counted starting from your first turn after finding any item via Foraging (or drinking water that you discover). So for example, if I find a Wild Cabbage and I have 1 point in Foraging, I can expect to find another item or fresh water in exactly 197 game turns, provided that on the 197th turn I walk onto appropriate terrain for foraging. Waiting or performing any action other than walking on the turn you would otherwise find an item will cause you to miss that item and you'll have to wait another full cycle.
The counter seems to reset itself to a random value within an appropriate range whenever your Foraging skill level is changed, whether by investing at a level-up, training, reading a skill book or equipping/un-equipping items that provide a bonus. Example, if I had 1 point in Foraging and read a skill book to increase it to level 3, the counter would be instantly set to a random value from 1 to 191 turns (I'm assuming the random value ranges from the minimum to the maximum for the new skill level, but that's only an educated guess at best).
So with Foraging at level 10 it will take 170 turns, and at level 25 (the highest useful level for finding new types of items) it will take 125 turns between each item.
An interesting thing to note is that (assuming no conditional statements are in place) at level 67, the number of turns required to find another item reaches a value of -1. This likely explains why things "start to go weird" at that value, as stated by another user in a previous thread:
As for what items are available at what levels of the skill, it follows a consistent pattern of introducing one new item each skill level with the exception of skill levels 2 and 3 (Foraging Skill level on the left, new item(s) available starting at that level on the right):Chaotic Newt Ral wrote:There are several issues with foraging.BasiliskWrangler wrote: Usually - a widget will have a (item name) in parentheses
Widget() is one of them:
(tested with Foraging Skill 66. Above that things start to go weird)
1 - Bittercup Seeds, Wild Cabbage, Water
2 - Nothing new
3 - Nothing new
4 - Yambi Berries
5 - Plumpcot
6 - Brimstone
7 - Mandrake Root
8 - Sulfur
9 - Spider Silk
10 - Noximander Venom
11 - Mercury
12 - Belladonna
13 - Ambergris
14 - Raven's Heart
15 - Willow Bark
16 - Dried Brainstem
17 - Dwarvish Mellowleaf
18 - Stinkroot
19 - Anise
20 - Widget ()*
21 - Wormleaf
22 - Black-spotted Shroom
23 - Toadis Pollen
24 - Ectoplasm
25 - Auricflax
*Note: The "Widget ()" is likely supposed to be a different item. There doesn't seem to be any level that makes Corpse Ash available, so maybe it was intended to be the level 20 item but there is a bug?
By the way, I haven't used anything but the playable game itself for any of this. I have tested and re-tested each level of Foraging extensively in-game and am fully confident that my list is 100% accurate.
Due to my method of testing however, the chance of finding food versus reagents at various levels of Foraging is not something I will be investigating. That would require far more data collection than the resulting information would be worth. If I had to make an educated guess I would say that there is an equal chance of encountering each of the items you are able to find at your current level of Foraging skill, regardless of what type of item they are. This includes finding fresh water.
Predetermined Seed Mechanics
When playing with the game rule for a predetermined seed to discourage saving and reloading, it seems that each wilderness tile suitable for foraging is assigned one or two items as part of the seed, and the assignment is not changed until your Foraging skill level changes. The seed is determined for all possible skill levels of Foraging when the game begins, so specific tiles will always contain the same item(s) at specific skill levels in a particular game.
Each tile will yield only a single type of item (for example, Brimstone) as long as you do not forage on it twice in a row. So if I receive Brimstone from one tile, walk until I receive a different item somewhere else and then return to the Brimstone tile, it will still yield Brimstone. If I farm the same tile repeatedly it will alternate between two items (say, Brimstone and Plumpcot) as well as occasionally yielding fresh water, seemingly in place of either of the main two items. The precise mechanics of this are still a bit foggy but the above rules seem to apply consistently so far.
If I were to change my Foraging skill level in any way, for example by equipping an item with a bonus to make it level 15 up from 12, the tile that yielded Brimstone and Plumpcot at a Foraging skill of 12 would likely now yield something different. If I remove the ring so I have a skill level of 12 again, the tile will revert to yielding first Brimstone and then Plumpcot. There seems to be a carry-over period wherein the first item you receive after changing skill levels still coincides with the old seed, so immediately after switching to level 15 I may still find one Brimstone at that spot, but then begin alternately finding Yambi Berries and Spider Silk, or just Yambi Berries if I am also farming a different tile.
To put the implications of this as simply as I can, with any odd-leveled Foraging skill (25 or higher being ideal), you could abuse the auto-walk feature to quickly walk back and forth between two tiles that both yield favourable items, collecting one item from each tile alternately. The item you collect from each tile would never change because you would not collect from the same tile consecutively. With an even-leveled Foraging skill you would have to find a tile whose two items are favourable and you would have to deal with sometimes finding fresh water as well, since walking back and forth would always end up farming the same tile. This is because of the formula for turns outlined at the beginning of this post.
I hope that wasn't too confusing and that some people find it interesting or helpful. I may do some more testing of these mechanics later but not for awhile. Happy foraging everyone!