I am interested to hear what success you have.
I am also wondering how one would decide what to test for when little information about potential contaminants is available.
In my case I am not worried about herbicides/pesticides; the state of the property, history recounted by neighbours, and vigorous growth of broadleaf plants in even the most respectable of the 'fields' all argue convincingly that no deliberate application of anything has happened for at least one and probably 2-3 decades.
I do wonder about contamination from a long ago dump area, obviously at some point garbage was piled up from the original homestead, and later a mechanized farm and small sawmill.
How worried
should I be about burn pile residue mixed with my soil, in food-growing areas.... when I have no data about what/when was burned?