I was trying to place the top of a sunflower with /setblock (setblock ~ ~ ~ 175 0, 175 1, 175 2...) until I eventually crashed Minecraft. I don't know if it works in singleplayer, but I think it's caused by the top of a two-block flower not having a bottom block. I had a friend go to the same chunks I was in when I crashed and as soon as the chunks were loaded for him, his game crashed.

I will post the crash report in the comments.