I vary the spicing according to what I plan to serve them with and use one of two approaches. For general, 'all-purpose' pickled asparagus you can use conventional pickling sorts of spices. I skew to tarragon or fennel or aniseed if serving with chilled fish or in a cold salad that includes fish sometimes, will make a spicy version (with hot peppers, fresh and/or dried) for app platters, and so forth.
You certainly can pickle and pressure can. I just make 'quick' versions.
A conventional quick approach:
In a pot combine 1 part vinegar (I mostly use white wine, white balsamic or rice) with 1.5-2 parts water (so, e.g., 1 c vin with somewhere between 1.5 and 2 c water--start with the lesser and taste).
Stir in about 2 T kosher salt, 2 T sugar, 2 T pickling spices* aand bring to a boil over med-high heat. Simmer, covered, 15 min.
Add asparagus (about a typical bunch), wood ends snapped off of course (adding a little more water if the brine doesn't cover the asparagus), then simmer till the asparagus is faded but still crisp-tender, 3-7 min depending on their thickness. Quickly pour the asparagus and the brine into another pot (or large bowl) and add a heaping cup of ice cubes to stop the cooking. Let cool further on the counter then pack with some of the brine and chill in the fridge. Serve chilled or at room temp. The flavor gets more intense with time.
* You can vary these amounts but this is a good starting point. You can add slices of shallot or onion or garlic; sliced or whole dried or fresh peppers of whatever heat level you fancy; peel or zest from lemon or orange.
A different approach (for when keeping the asparagus color bright green is important):
Put a bunch of snapped asparagus in a pan or pot, cover with cold water, and add a T of salt. Bring to a boil then cook 1 more minute. Immediately shock. Drain well and put in a shallow container or a Zip-loc.
Meanwhile, in a small pot mix 1/2 c vin of choice, 1/2 c water, 1 t salt, 1 t sugar, and a total of 1 T spices (plus any optional) fresh stuff you want like shallot, garlic, peppers) then bring to a boil over medhigh heat; cover then simmer 5 min. Remove from heat and allow to cool completely. Pour over the asparagus then chill in the fridge. Wait for at least 5 hours before consuming and up to 2 days. After a couple days the color will start fading.