I've searched the forum and found only some suggestions about alchemy so I guess it's fine to post it.
As herbs and plants, gardener and forager credos alongside with wound treatment are a big part of a game I think adding more forageable plants could improve the game.
Medicines
Garlic Allium sativum - could be used as an ingredient in cooking or as a mash to treat wounds
Horseradish Armoracia rusticana - wound treatment, food ingredient (craftable ćwikła)
Oak bark - infection treatment
Willow bark - natural painkiller, could be used cure wounds
Soapwort Saponaria officinalis - subsitute for a bar of soap
Comfrey Symphytum officinale - root mash could be used to treat wounds
Drugs
Fly agaric Amanita muscaria - could be used as an ingredient for a berserk potion/snuff. Viking are said to have used them to enter a state of fury.
Calamus Acorus calamus - its rhizome is said to have hallucinogenic properties
Wormwood Arthemisia Absintium - said to be hallucinogenic, absinth could be made from it. (potential green fairy curio)
Smokeables
Salvia Salvia divinorum - could give buff similar to hemp buds or be used in hearth magic
Coltsfoot Tussilago farfara, Mullein Verbascum- when smoked, are said to treat cough, throat and pulmonary diseases; could be used to treat coaler's cough
Poisons
Deadly nightshades Atropa belladonna, Foxgloves Digitalis, Henbane Hyoscyamus niger, Wolf's bane Aconitum
Those might be used to create poisons. Creates future possibility for traps, poison arrows, blow darts etc.
Drinkables
Mead - could give satiation buff
Flower or fruit wine - satiation buff (e.g. elderberry flowers or apples could be used to make wine)
Kumis/Kefir - produced from milk, satiation buff
Tinctures - would require implementation of alcohol still; could be used in alchemy or to make and manage medicines
Edit: I did overlook some things, my bad. I leave Amanita and nightshades though as it would serve a different purpose as it exists now in the game.