Hmm, I am *not* common with FC, in a regular Linux setup, you have to
- use the usbstorage driver (modprobe if it is present)
- mount the drive
For you stated that in bootup, the drive is "seen", I assume the driver is there.
So, the thing you might miss is mounting the drive. For once, you can do it (as root) by
mount -t vfat /dev/sda1 /mnt
(assuming you have a mountpoint /mnt already made using mkdir /mnt, probably you wish to mount it to /mnt/usb or somewhere, and assuming you have the usb drive maped to sda1, which should be true in most SCS-driveless systems).
If this does the trick, consider adding it to you fstab file, so you can mount it in your regular account.