Can you attach a USB drive to the motherboard with SATA?

If your motherboard has a 4-pin USB internal header, you can get an eSATAp adaptor for it.

Other than that, I cannot find a SATA->USB adaptor only USB->SATA.

Of course, you could remove the drive from it's USB housing and put it in a housing with a SATA connection exposed.

Alternatively, you could mount it internally if you have room. It wouldn't be portable then of course.