My personal favorite:
Canis Root + Mora Tapinella + Imp Stool = Paralyze & Drain Health
That's my favorite too. excellent poison in the field, fetches good coin, and helps level alchemy very nicely.
For healing, use Blue Mountain Flower + Wheat instead. Fortify Health + Restore Health.
For Fire Resistance: Dragon's Tongue + Snowberries
For Frost Resistance: Purple Mountain Flower + Snowberries
For Shock Resistance: Glowing Mushroom + Snowberries
For Magic Resistance: Lavender + Tundra Cotton
These are good to carry around, just in case you meet a dragon or a mage. You can make Dragon's Tongue + Purple Mountain Flower + Snowberries for a potion with 2 effects. etc.
Salt becomes plentiful after you play the game a bit. You may also like Deathbell + Red Mountain Flower + Salt: Slow + Damage Health (good money and often useful)
I also like Garlic + Salt + Juniper Berries = Regenerate Magicka + Regenerate Health. Useful and expensive. But you can't grow garlic or salt.