I've got Neenah 65# cardstock like that, with the little color flecks in it - it's called "Stardust" but I've only found it in white & ivory.
I just googled & found this -- French Papers makes a "Speckletone" flecked cardstock in a good variety of colors, including a few kraft tone colors. It looks like some colors are only available in 80#, and other colors have several choices. Their site is at:
Speckletone Paper | Colored Paper, Custom Paper | French Paper Co.
I haven't tried their paper before, but I think I might order a sample pack! I *love* the little flecks in the paper, and have always wished that Stardust came in other colors & weights!