Except it can't be made without ruining a quest.

http://fallout.wikia.com/wiki/Mushroom_Cloud






ok then...

From that page, under the header Bugs;

The item Pile of Night Stalker Eggs is a quest-related item which you can only obtain one of throughout the entire game. Because of this, Mushroom Cloud can never be obtained without the use of console commands. It can be assumed that Mushroom Cloud was intended to use the non-unique night stalker egg item in its crafting instead.

:\

*sighs* yet another oversight.