Clean and wash the corn on the cob. Brush off the mushrooms, cut off the ends of the stems at the head. Do not wash mushrooms.
Bring the water to the boil, add salt and cook the corn on the cob for 15 minutes. Drain the corn and pat dry with paper towels.
Put the mushrooms on the skewers, drizzle with lemon juice and pepper. Melt the herb butter, then brush the corn on the cob and mushroom skewers with it.
Grill for 5-8 minutes, turning several times, and brush with the herb butter every now and then.