That being said, wild herbs such as sage and thyme are excellent in herbal recipes. You'll want to carefully pick the areas you harvest in, however. Stay away from highways, rivers that are polluted or have EPA warning issues against them, public parks, and farmland. Highways and polluted rivers are obviously not ideal. Too many chemicals involved to give you a decent product. When it comes to farmland, consider that most farms use pesticides and fertilizers to grow their crops. You never know when the chemicals were used, so they might be at their most potent when you collect your herbs.
Public parks are an interesting conundrum. In some cases, they're perfectly safe in regards to chemicals, but you may not be permitted to gather wild plants there. Many, if not most, public parks have rules against picking the flora, so it's generally best to find a forest, field, or other area that is not specifically designed as a public park. If you do want to gather on parkland, make sure that particular park allows you to harvest herbs before you gather up your supplies and set out.
The other problem you may encounter is gathering on private land. Not all fields and forests are fair game. Even if it looks like the field is abandoned, it could still be owned by someone. Herbs on private land belong to whoever owns the land. Sure, your neighbor might not mind if you gather the dill growing freely in his backyard, but I bet the farmer with a field of ginseng won't be as willing to part with a crop that makes him money. Ask first.
A further word of advice: don't collect mushrooms, no matter how good your guide is. My great-grandfather was an expert, and even he eventually picked a poisonous mushroom. He died the next day. Mushrooms are sneaky devils, so if you are using mushrooms in an herbal recipe, buy the mushrooms.
When you are gathering your herbs, you should make sure you have the correct supplies. You'll need something to cut the herbs since tearing damages the plants. You can use your bolline or a sharp pair of scissors. You'll also need something to carry herbs home in. Do not use plastic bags as these promote rot. Instead, get yourself a mesh bag, preferably one with several different pockets for different herbs. The mesh allows the air to pass freely around the herbs, keeping them from even starting to rot. They'll dry instead, which is a much better option.
If you keep the above in mind while you're searching for wild herbs, you should be well on your way towards gathering something worthwhile. For myself, I gather wild cedar, pine, willow, birch, and a few other trees. I also have access to wild sage and thyme, though I prefer to grow my own. You can choose which plant materials you'd like to grow, which you'd like to buy, and which you'd like to try gathering wild.
