Mash the garlic,herbs, and half of the butter together into a rough paste. Divide he herb butter among the lamb chops, spread a bit inside the tails and the rest on top. Tie the chops into tidy rounds with kitchen twine.
Arrange each chop on a piece of aluminum foil and place a lemon slice and a mint sprig on top of each. Smear the remaining butter over mushrooms and arrange them equally among the chops. Season with salt and pepper. Seal the foil packets, and set on a baking sheet.
Bake about 20 minutes for medium rare. Transfer the packets to serving plates and allow the guest to open them at the table.