Experts and BHG readers answer.
Raised bed garden
Crabgrass is an annual grass that germinates from seed each year. If you have covered it up with several inches of new soil, it likely won't push up through the soil this season, but the seeds will be there, and likely will sprout next year. If the grass is something other than crabgrass (for example, quackgrass, which is a spreading perennial grass), it could grow up through the soil. For something like quackgrass, you'll need to kill it with glyphosate (round-up) or smother it with black plastic.