Fibonacci-like Differential Equations with a Polynomial Non-Homogeneous Part

We investigate non-homogeneous linear differential equations of the form $x''(t) + x'(t) - x(t) = p(t)$ where $p(t)$ is either a polynomial or a factorial polynomial in $t$. We express the solution of these differential equations in terms of the coefficients of $p(t)$, in the initial conditions, and in the solution of the corresponding homogeneous differential equation $y''(t) + y'(t) - y(t) = 0$ with $y(0) = y'(0) = 1$.