This needs to be bumped to the top Google hit for "button down for short-neck transmascs," I stg. I'm 5'0" with a really round face and short neck (but broad shoulders) and this button down fits so well. The height of the collar is extremely low, to the point where I'd even consider wearing it buttoned all the way up. Every men's shirt I've bought makes me look like an 11 year old dressed up for school picture day, but this shirt makes me feel like a sexy professor.
The material is also sturdy and high quality. My only complaint is the shoulders are a little stiff, but I think they will relax as I wash/wear. I will be buying in more colors. (For size info, I originally bought size S, was too large, now size XS).