Monroe claims that burdock root has properties much like aspirin (i.e.: painkiller, reduces fevers), and that it tastes like an old tennis shoe. But while burdock really is a diuretic, it does not act as a painkiller, and the flavor is good enough for it to be a popular vegetable in some countries. Monroe also made it sound as though burdock was hard to find, when it's actually an invasive in most of the US.
There is NO possibility a child would be returned to parents immediately without the presence of SOMEONE from a child protective service or mental health - to monitor the reunion, especially a near feral child, and to arrange counseling.
The police exclude competing drug dealers/growers as suspects because the first victim's cannabis plants were not taken. However, it does not really make sense to "take" immature cannabis plants. Re-planting them means a lot of stress for plants. Digging them up is a lot of work and many of them will either not survive being re-planted, or yield a diminished crop of poorer quality. Getting Blake's crop off the market could in itself be motive enough.