For a compact Kähler manifold of dimension $2n$, is there a classification of the homological $n$-cycles which are supported in a compact Lagrangian submanifold?
The main example for this question is a projective manifold with the symplectic structure coming from Fubini-study metric. Using symplectic Picard-Lefschetz theory one can describe many Lagrangians which are vanishing cycles, and explicit computations of the monodromy group helps a lot.