Wilson current mirror
I would use bipolars, not FETs.  The FETs have to be particularly well matched for this to work, which is difficult to guarantee with discrete parts.  Use two NPNs.  With enough emitter resistance, you should be able to to better than 5%.  Keep in mind you can't use 5% resistors if you want accuracy better than 5%.  Try something like this:



If that doesn't do what you need, a opamp circuit should do it, but will be a bit more complex.