Even when plants don't extract significant amounts of material, they can be useful in detecting sources. A paper about using synchrotron analyses to detect gold in eucalyptus comes to mind.
https://news.mit.edu/2016/nanobionic-spinach-plants-detect-e...
> gold particles in Eucalyptus leaves and their relevance to exploration for buried gold deposits
Would love any other recs like this.
https://www.sciencedaily.com/releases/2012/12/121211095007.h...
( Also used in parts of Africa)