Spices are aromatic seasonings that come from the bark, (cinnamon), buds, (cloves), fruit, (paprika), roots, (ginger), or seeds, (nutmeg), of plants. Herbs are the leafy parts of plants such as basil, mint, or oregano. Spices should be kept in a cool dark cabinet. Heat and light will facilitate deterioration.
Most herbs can be found dried or fresh and can be used either way with ease. Herbs are considered ro be the leaves and greener parts of the plant - the seeds, bark, roots, etc. are normally considered a spice. Some plants are both.
Tomato dishes can almost always benefit from a few grinds of nutmeg. It's amazing how much depth and complexity it gives to otherwise same-old-same-old Italian and Mexican dishes.
Fresh herbs are great for garnishing and are perfectly healthy and all-natural food while dried herbs make your food perfect from the start it is added during cooking, plus, they give wonderful and zestful aroma to dishes. A great experience of mine.
My french cookbooks tells me to use twice as much fresh herb when converting from dried. I always found this funny, because it does not make much logical sense. I've only listened to them once when I was making soup, and it came out so horribly over-flavoured.
Plants of the Mint family (Mint, Peppermint, Spearmint, Catnip) have square stems. This can help to identify them in the wild.
Wild Onions can be identified by their flower heads. The poisonous Camas has a spike of flowers, the onion and relatives (chives, leek, garlic) have a ball of flowers, and the ball shape of the flower bases remains after the flowers are gone.
Dried herbs are best when used with oil (or butter, fat) or water - this way they can infuse the oil or cooking liquid. Make sure to crush the herbs with your fingers or saute them a bit to wake them up. Crushing a bunch of them in a mortar and pestle also works very well.