I think hundreds of different plant extracts have been reported for the synthesis of different Metals Nanoparticles. If you want to know about which plant is used for which metal, you can find in this file.
Green tea extract ,also extracts contain phytochemicals such as terpenoids, flavones, ketones, aldehydes, amides, amino acids and carboxylic acids are the primary active ingredients for nanoparticle synthesis .
There are several plants used for nanoparticles synthesis, the plants which have some medicinal properties are consider as the most for green synthesis. Because these plants contain some active Phytochemicals which are responsible for the reduction of different ions like gold ion. Keep in mind don't use the plant which are edible. Edible plants generate food security issues.