Which plate boundary would you expect to find a metamorphic rock?

Convergent plate boundaries.

Metamorphic rocks are formed mainly in the lithosphere layer of the earth. In this layer, they are found where there are high pressure and temperature. But in case of too high pressure and temperature, these same metamorphic rocks melt down to form magma. Metamorphic rocks are found in abundance at convergent plate boundaries, but they can occur in other areas as well, if there is a suitable high pressure and temperature.