Yes, wineries will typically allow you to bring your own picnic basket and savor your own meal at no charge – But! They will generally ask you to purchase a bottle of wine or a tasting in exchange for the ambiance and stunning views.
Pro tip: Laird Family Estates actually offers a special called “Bottle & Blanket Tasting” (just bring your own snacks, and they will provide the picnic blanket, wine, and stellar location!)