Q. Need detailed resources on milk thistle (Silybum marianum) and/or bull thistle Bull Thistle (Cirsium vulgare).
Link to the U. S. Forest Service information on Bull Thistle (Cirsium vulgare) here.
The USDA PLANTS database plant profile of Bull Thistle is here.
Link to the USDA PLANTS database information on Milk Thistle (Silybum marianum)here.
These sources contain quite a bit of information on each plant -- just keep scrolling down the pages for more details and links. They should provide the detailed information that will help you with your school project. The Weed Science Society of America may also be a source of information for you.