Contrary to what you read here a mushroom anchor is designed to work upright and buried. If not it will "walk " back and forth and you will find your boat high and dry in a big blow. That is how so many boats ended up on shore after "BOB" here on Cape Cod. Have it put down and set to start out. Then it will work itself in over time. How much time depends on the movement of wind and tide.Also have it checked every season to ensure that it is set and the gear is up to spec.
Do not rely on weight alone to hold your boat!