Note that mostly medicine cats, and their apprentices are to know about these. If suddenly every clancat knows what every herb does, this is going to be taken out of public sight, and only available to med cats, and their apprentices. It's okay to know a few of the common/simple ones, but not every one.

Borage Leaves:
Star-shaped (blue or pink)/Hairy leaves.
Must be eaten.
Increases Queens milk, and reduces fever.

Burdock Root
Tall stemmed, sharp smelling thistle with dark leaves. Dig up roots.
Roots must be chewed into pulp by medicine cat, and put on wounds like rat bites.
Cures infection.

Catmint (aka Catnip)
Delicious smelling, leafy, difficult to find in wild.
Common in twoleg gardens.
Best Greencough remedy.

Chervil
Sweet smelling with large, spreading, fern-like leaves and small white flowers.
Juice from leaves can be used for infected wounds.
Chewing root helps bellyache.

Cobweb
Spiderwebs (lacking the spider, of course.)
Wrap around wounds.
Keeps wounds clean/stops bleeding.

Coltsfoot
Flowering plant, similar to dandelions, with yellow or white flowers.
Leaves chewed to pulp, then eaten.
Helps short of breath.

Comfrey
Large leaves, small bell-shaped flowers, in pink, white or purple.
Fat black roots chewed into poultice.
Mends broken bones, soothes wounds.

Dock
Similar to Sorrel.
Chewed up and applied to scratches.
Soothes scratches.

Dried Oak Leaf
Collected in autumn.
Stored in dry place.
Soothe scratches.

Feverfew
Bush - flowers like daisies.
Eaten.
Cool down body temperature. For cats with fever or chills.

Goldenrod
Tall, bright yellow flowers.
Poultice.
Helps heal wounds.

Honey
Sweet, golden liquid made by bees.
Difficult to get without being stung.
Soothes infections and throats of cats who've inhaled smoke.

Horsetail
Tall. Bristly stems. Grows in marshy areas.
Usually chewed and applied as poultice.
Treat infected wounds.

Juniper Berries
Spiky dark green leaves. Purple berries.
Berries are eaten.
Soothes bellyaches, and helps those with troubles breathing.

Lavender
Small purple flowering plant.
Cures fever.

Marigold
Bright orange or yellow flower. Grows low to ground.
Petals/Leaves chewed and applied as poultice.
Stops infection.

Mouse Bile
Bad smelling liquid.
Dab moss soaked in bile on a tick. Wash paws thoroughly after.
Only way to kill ticks.

Poppy Seed
Small, black seeds shaken from dried poppy flowers.
Eaten. Not recommended for nursing queens.
Soothes cats suffering from shock/distress. (Makes them tired)

Stinging Nettle
Spiny green seeds//Leaves.
Seeds - eaten. Leaves - Applied.
Seeds for a cat that's swallowed poison. Leaves to reduce swelling from wound.

Tansy
Strong smelling. Round yellow flowers.
Eaten in small doses.
Good to cure cough.

Thyme
Eaten.
Calms anxiety/frayed nerves.

Watermint
Leafy green plant. In streams/damp earth.
Chewed to pulp, then fed to cat.
Helps bellyache.

Wild Garlic
Roll in patch.
Especially for dangerous wounds such as rat bites.
Prevents infection.

Yarrow
Flowering plant.
Leaves made into poultice.
Applied to wounds/scratches to expel poison.

Note:

Deathberries aka Yew Berries
Red berries.
NOT medicine.
Poisonous. Especially to kits and elders, possibly fatal if not instantly treated.
DEADLY.