select multiple files or folder for upload in rails

I have a rails app where users upload files. However, as it stands if users want to upload more than one file, they have to load those files one at a time. This doesn't make sense if they want to send 100 files for processing so I was wondering how I can make it so they can upload all files from a folder, or recursively the contents of an entire folder. For example, say they have:

Desktop
|
+--Folder of files
   |
   +--Folder of files of type A
   |  |
   |  +-- file1
   |  +-- file2
   |  +-- file3
   |  ...
   |  +-- file50
   |
   +--Folder of files of type B
      |
      +-- file1
      +-- file2
      +-- file3
      ...
      +-- file4

I'd like to give them the option to select Folder of files and upload each of the 50 files in Folder of files of type A and Folder of files of type B. Are there any gems that allow for upload of multiple files or entire folder with one selection? or will I have to write one from scratch?