In [1]: a = galois.Poly.Random(5); a
Out[1]: Poly(x^5 + x, GF(2))

In [2]: a.field
Out[2]: <class 'galois.GF(2)'>

In [3]: GF = galois.GF(2**8)

In [4]: b = galois.Poly.Random(5, field=GF); b
Out[4]: Poly(251x^5 + 133x^4 + 170x^3 + 212x^2 + 40x + 32, GF(2^8))

In [5]: b.field
Out[5]: <class 'galois.GF(2^8)'>