You have Canada Thistle (Cirsium arvense). More info in this weed ID app from MSU: http://www.msuturfweeds.net/details/_/canada_thistle_18/
Canada thistle is typically labeled difficult-to-control. Applications of 2,4-D, MCPP and dicamba will not usually provide acceptable control of Canada thistle. Triclopyr and clopyralid used alone or in combination with each other or phenoxy herbicides provides the best results in the trials at MSU. Fluroxypyr, the replacement for clopyralid in many pre-mix combinations, does not have activity on bull thistle. Primary application timing should be targeted for early-fall. Multiple applications (28-day interval) may be necessary.
You might also consider using a weed killer containing glyphosate, but remember glyphosate is a non-selective herbicide and will kill any plant it contacts. Check with your local nursery for products containing these herbicides to kill Canada thistle.
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