The issue of PCs wanting gather and make use of poisons is becoming more prevalent, so I thought I would clarify the rules for this before we go any further. According to the DMG (p 258) harvesting one dose of a poison requires a DC20 Intelligence (Nature) check or proficiency in a Poisoners' Kit can be substiuted but it's still an Int roll. If the check fails by 5 or more, you become exposed to the poison and must make a saving throw or suffer the poison's effects. Note that this procedure takes 1d6 minutes for 1 dose....................