In case you get a building from a stone head gift, you will only have one shot of that building - after you place one plan, it will disappear from the buildings panel.

 

Be warned that if you place a plan and delete it right after, you will not get a refund of it. In other way, if that plan or already constructed building gets destroyed, you will not have a refund of it. This means that you have one plan of that building, and nothing else. Usually, there is nothing on the building's panel indicating that you only have one shot of a particular building, you have to pay attention to the rewards you get from the stone heads. This doesn't happen in some unofficial singleplayer mods - there will be a symbol warning that you only have one shot of that building. That's helpful.

 

There is a trick that allows you to build many plans of that building, while having only one shot of it - hold Ctl, select the plan, and place it as many times as you want - take note that once you release the Ctl, you can only place one last plan. This is a trick that doesn't work on some unofficial campaign mods though, since the creators of that mods scripted it so well to avoid this glitch - if you try to do this on those campaigns, you will get a warning message.