The name Garner is a boy's name of Latin origin meaning "granary". Garner and is often added to lists like Celebrity Surnames as Firsts and discussed in our forums with posts like "Build a Sibset With Middles".
From the experts:
Garner is an unncommon word and surname with some prospect of garnering popularity, especially now that Jennifer Garner and Ben Affleck have given it to son Samuel as his middle name, and Jessica Alba and Cash Warren have used it as the middle name of second daughter Haven. Garner is also Cash Warren's middle name. Gardner or Gardener is another, similar though unrelated possibility.