I have Vagrant (1.7.4) configured with the default configuration vagrant initfrom using the latest version of VirtualBox (5.0.16 r105871) in OS X (10.11.4) and the latest version ubuntu/trusty64(v20160323) .0.0).
My virtual machine has an appropriate version of guest add-ons, but I cannot get the shared directory /vagrantto work. The directory /vagrant/exists in the virtual machine, but if I run it ls, then it is completely empty. If I have a touchfile, it appears in the guest folder /vagrant, but does not synchronize with the project folder on my machine and disappears upon reboot. The virtual folder is displayed in the VirtualBox GUI:
http://i.imgur.com/yM1wuj5.png
EDIT: Vagrantfile:
Vagrant.configure(2) do |config|
config.vm.box = "ubuntu/trusty64"
end