I was having problems with docker toolbox and windows 10 mounting. I found article http://support.divio.com/local-development/docker/how-to-use-a-directory-outside-cusers-with-docker-toolboxdocker-for-windows
But still didn't work, so what i did was instead of /home/docker/projects i used /e/Projects/myproject. In Virtualbox i added new shared drive named e/Projects/myproject and location E:/Projects/myprojects after that my mounts worked.