As an aside, I've been trying to create a plant-based creature, that could be butchered for edible plants. I used plump helmet man as the inspiration, but unfortunately, I don't think this is currently possible:
A body made of vines.
[USE_MATERIAL_TEMPLATE:SM_VINE:STRUCTURAL_PLANT_TEMPLATE]
[STATE_NAME:ALL_SOLID:vine]
[STATE_ADJ:ALL_SOLID:vine]
[STATE_NAME:LIQUID:melted vine]
[STATE_ADJ:LIQUID:melted vine]
[STATE_NAME:GAS:boiling vine]
[STATE_ADJ:GAS:boiling vine]
[PREFIX:NONE]
[EDIBLE_VERMIN]
[EDIBLE_RAW]
[EDIBLE_COOKED]
[MEAT] <- butchered vines aren't stockpiled without this
[BUTCHER_SPECIAL:MEAT:NONE]
[MEAT_NAME:NONE:vine:vine]
[TISSUE:VINE]
[TISSUE_NAME:shambling mound vine:shambling mound vines]
[TISSUE_MATERIAL:LOCAL_CREATURE_MAT:SM_VINE]
[HEALING_RATE:100]
[SCARS]
[MUSCULAR]
[FUNCTIONAL]
[STRUCTURAL]
[RELATIVE_THICKNESS:2]
[CONNECTS]
[TISSUE_SHAPE:LAYER]
[TISSUE_LAYER:BY_CATEGORY:ALL:VINE]
The [EDIBLE_RAW] and [EDIBLE_COOKED] tags seem to be enough for the resulting 'vines' to be edible/cookable, however without the [MEAT] token, they won't be stored in a food stockpile. The best I can do then is to create a meat that is merely named like a plant. It's stored in meat barrels, and counts as meat.
Similarly, I tried creating a shearable tissue layer of leaves with the hope that they could be used for plant thread, but without having played around with this too much, I don't think it's possible.
The problem at its core is that you can't control the item token of the butchering/shearing yield. When you butcher/shear you get MEAT and CORPSEPIECE, and you don't have any control over that. You could make a custom reaction to turn a "leaf" corpsepiece into plant thread, but you couldn't get a sheared product to work with the default plant processing reaction.
Unless I'm wrong, and anyone has some other thoughts about this?