Any of the items that can be used in the processor will show under the "Processable" tab in the GUI while accessing a processor as shown below.

Wood

Stone

Obsidian

Iron

Diamond

Lumite

Note that all slabs in here can be turned into stairs.

Dirt

Grass

Peakstone

Ice

Bedrock

Limestone

Adobe

Blue Adobe

Red Adobe

Yellow Adobe

Ok so on May 8th, we got some new corner roof & stairs we can get from all roof/slopes and stairs by throwing them in the processor.

I'll replace this section with the appropriate table soon-ish, thanks for your patience.

Chromatic aka "RGB er... CMY" (n4)

Crops & Seeds

Other Extractions & Conversions

Craft-like recipe

Any of the items that can be used in the forge will show under either the "Forgeable" tab or the "Fuels" tab in the GUI while accessing a forge as shown below.

Ores beside coal, by increasing values

Others, by alphabetical order of initial ingredients

There are 4 different level of fuel : 1, 2, 3 and 10. Each divide the basic time by it's level. So for exemple, a level 2 fuel would forge obsidian in 10 seconds instead of 20 seconds.

Whenever you get a fraction, such as level 3 on obsdidian (6,666666....), it is rounded down (so 6).

Leaves (except corrupted), wood (idem) and wood items, tall grass, etc. Essentialy stuff that you will find on the surface. Most are easily renewable. Some items such as wood rods require less ressources overall.

Coal (1), Sulfur (1) and Hardened Lava (4).

Corrupted wood and leaves. Tar sandwich.

Tar Bread and Tar Soup. I have not personaly confirmed Tar Soup, but item description seem to indicate as much.

Wood to Lumite

This make the bulk of both tables, and is composed of two basic blocks (Wood/Stone and equivalents) and ores (Coal excluded, but useable fuel and important crafting mats in it's own right).

They are generaly found from top of the world (Wood) to bottom (Lumite), they have been ordered as such. On old worlds they used to overlap a little, in new worlds each ores has it's own layer (obsidian = mostly fossil, iron = stalactite, diamond = lava, lumite = corruption).

Incidently, all of those materials are key components in making Tier 1 to Tier 5 power cell. Conveniently, they require at least one degree less to reach (pull, or navigate to be able to place extractor).

Chromatic Flowers

Blue is from Elderwood (close to mountain/snow/tundra). Red is from Ashenwood (forest/grassland/woodland, some canyon/mountain and other locations as well), Yellow is from Cragwood (id. Ashenwood).

All of those (and other flowers) drop from various creatures, wheter hunted or harvested.

Chromatic variant also drop from Treasure Chests at 8 base drop, multiple possible but rarer.

Or you can get the pigments directly by harvesting (tamed) Keepa on favorite food.

Crops

Initialy, all crops can be found except wheat. Those initial "naturaly occuring" always yeild one food item. Horned Melon is the hardest to get, located in the Jungle (detritus). Crisphead Lettuce & Turnip grow on grass. Wheat seeds are gotten from pulling Tallgrass or Savanah Tallgrass. Preliminary data seems to indicate Savanah Tallgrass drops are higher.

Others

Fossils
From deposits in the fossil layer or top of stalactite. Drop from dustdevil.

Tourmaline
From deposits in the stalactite (bottom?) and lava layer. Drop from warmworm.

Mold
From deposits in the stalactite layer.

Vines
From some Cragwood and Wildwood "naturaly occuring" blocks. From Wildwood placed vines (hanging). From Leafie (all type, or so, data collection underway) drop but in this instance minor.

Ice
From Ice Cap, freezing water, and at least drop from Artic Miru harvest (tamed).

Snow
From Snow... where it's cold (question I've been asking myself and not took step toward answering : is it regenerating on top of cold enough structures (naturaly or artificial)?

Beeswax
From some treetops, from farming through Queenbee (see Brainsloths' post/discussion), through chest and Silver Keepa (hunted) drop (n5)

Chizzard Gizzard
From Chizzard (any) drop (any). See Usefull data in near future (again, contributor welcome).

Mud
Although it say's from Stalactite layer (true, deposit form), you'll encounter it first under some shallow water (most lake, some shores). Drop from Rockster-type monster.

Pebble's Pebble
Drop from Peeble, be carefull of the "rally" skill of that little guy. Actualy, favorites foods on those guys are very basic and inexpensive, so it may be a viable farm and method to obtain cheap Rockster's Rock depending on your access to obsidian, extractor level and powercell level.

Sand
From beaches, dunes, desert, most underwater blocks and some deposits beyond those (named) points.

Any unspecified creature drop
Also, since I discontinued Usefull Data, the list from creatures should be (eventualy) exhaustive. Player input is always welcome.

n1 : Any wood or log beside corrupted wood. Same goes for shredded leaves.

n2 : Essentially a redo or inventory management feature since there is no loss both in time and quantity.

n3 : Name as shown in game. They are "bar-like" in appearance and obtained from refining (forging) ore. The only exception is Iron Bar that has the "bar" part in it's name.

n4 : This one if fun :) Some of you may remember RGB (Red Green Blue) from old analog screens. Turns out there is a world of difference between RGB and CMY (Cyan Magenta Yellow)... look it up!

n5 : I find this one amusing. Alphabeticaly, Crisphead trump all, yet it shows after Horned Melon in the inventory. I beleive this is due to "item type" being "lettuce" instead of "horned melon". This is (somewhat) evidenced in the seed name : Lettuce Seed (wich fits perfectly alphabeticaly).

n6 : Why would one want to do that. Granted bones now do something, beside helping you stand. Granted crystal shard are usefull. But those mats are readily available from any creatures and far less rare then Fossils or Tourmaline.

n! : A viable farming method as Peeble require very simple food.