We show that the \(\imath \) Hall algebra of the Jordan quiver is a polynomial ring in infinitely many generators and obtain transition relations among several generating sets. We establish a ring isomorphism from this \(\imath \) Hall algebra to the ring of symmetric functions in two parameters \(t, \theta \) , which maps the \(\imath \) Hall basis to a class of (modified) inhomogeneous Hall-Littlewood ( \(\imath \) HL) functions. The (modified) \(\imath \) HL functions admit a formulation via raising and lowering operators. We formulate and prove Pieri rules for (modified) \(\imath \) HL functions. The modified \(\imath \) HL functions specialize at \(\theta =0\) to the modified HL functions; they specialize at \(\theta =1\) to the deformed universal characters of type C, which further specialize at (t=0, \(\theta =1\) ) to the universal characters of type C.