Put a large platter in the oven to warm up. Gently melt the butter in a small saucepan over a low heat, then stir in the sea salt, spices and peppercorns. Remove from the heat.
To cook the asparagus, bring a little salted water (about 5cm deep) to the boil in a saucepan, making sure the saucepan is wide enough to fit the asparagus laying flat without crowding it. Add the asparagus and poach for 2-3 mins, or until a knife inserted into the thickest part of a spear can be pulled out with no resistance.
Meanwhile, return the spiced butter pan to the heat, then add the shrimp, wild garlic or herbs and lemon juice, basting the shrimps well. Taste and season, if necessary. Drain the asparagus and pile onto the warm platter, then pour over the shrimps and spiced butter. Garnish with the flowers, if using, then serve with chunks of crusty bread.