Let g be a cusp form on Gamma0(N). A harmonic Maass form F is said to be good for g if (i) the principal part of F at the cusp infinity has Fourier coefficients in Q(g), the field generated by Fourier coefficients of g over Q; (ii) the principal parts of F at other cusps are constants; (iii) the shadow of F is g/|g|^2, where |g| denotes the Petersson norm of g. In this talk, we will give explicit constructions of harmonic Maass forms that are good for certain cusp forms on Gamma0(N) when the normalizer of Gamma0(N) is a triangle group. A key ingredient is the evaluation of L-values of weakly holomorphic modular forms in terms of hypergeometric functions. This is a joint work with Hsu and Tu.