Ornithogalum umbellatum, star of bethlehem is often planted as an ornamental, and has escaped cultivation, due to its aggressive growth habit. https://oak.ppws.vt.edu/~flessner/weedguide/otgum.htm  

Your best option is to dig up the bulbs using a sharp spade. The plant multiplies from producing more underground bulbs. It does produce a flower that if allowed to mature, will produce seeds, but it does not reproduce as rapidly from seed. 
There are no selective herbicides for control. You can paint the foliage with a nonselective herbicide, active ingredient, glyphosate. This will kill desirable plants so you will have to shield them with cardboard if you spray or paint. 
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