In a large skillet, melt the butter. Add the morels and stock, cover and cook over moderately high heat until softened, 5 minutes. Add the asparagus, cover and cook until crisp-tender, about 2 minutes. Season with salt and pepper and cook uncovered until the broth is nearly absorbed, 1 minute longer.
In a large bowl, whisk the olive oil with the lemon juice and season with salt and pepper. Add the frisée, butter lettuce and chervil and toss to coat. Arrange the morels and asparagus on plates and mound the salad alongside. Drizzle with argan oil, if using, and serve.
Argan oil, which has an intense, nutty flavor, is available at zamourispices.com.