Good medicinal pioneer plants

I’m curious if you have any go to medicinals that are good pioneer plants as well, easy to get started and establish well in your system.

Well, our clearance of a redundant conifer plantation in UK gave an opportunity to see what popped up 'naturally' as a pioneer. Mainly silver birch (Betula pendula) trees! This is a wonderful medicinal tree, providing antiseptic and diuretic actions. But it does need good light so will soon die back if overshaded. It does also coppice well if you want to produce lots of leaf for tea and control the size to a bush. The leaf buds are magical to harvest in spring, though you need a lot to fill a cup, they can be infused in a carrier oil (such as sunflower or sweet almond) and heated gently with a little beeswax and shea butter to make an effective skin ointment - I give more detail on the making of Birch bud and sweet bay balm in The Medicinal Forest Garden Handbook.