Driving around the Tasman district at the moment you'll see St John's Wort (Hypericum perforatum ) in flower. It is classed as a noxious weed as it can cause poisioning of livestock so you are not supposed to propagate it in your garden. I collect it from the riverside to make herbal oil to treat hemmoroids, skin irritations and wounds. It is also reputed to help with burns. A few years ago it was popular as an antidepressant but I think the tea tastes like turpentine. Carefully identify plants before use, ragwort is also in flower at the moment and looks very similar, a good herbal will have accurate pictures, develop an eye for detail. To make the oil you pick flowers and buds on a dry day after the dew has dried, soak in oil, olive or almond for 6 weeks to 6 months then strain out flowers to reveal the lovely red oil, gently heat with other healing oils eg: calendula or comfrey in a double boiler and add a few shavings of natural beeswax to make a gentle healing ointment. I would suggest a healing prayer or karakia while combining ingredients, bottle in small glass jars, use within a year.