I've found asparagus hard to rinse totally free of grit, and morels even harder (all those little indents!).
Thanks for the tip! "Only a minute" to soak - I've erred on the side of a longer soak that sucks the vitality out of the green things. (Morels are brown. Hmmm.)

Salt water, I've read, helps pull debris from morels.

Now to find some of those elusvie Midwest mushrooms.... haven't seen even one this year!