Right about now your local grocery stores will begin having asparagus at a pretty decent price, since asparagus is what they call "in season." (To us in northern areas of the country this means that growers in warmer zones south of us are beginning to harvest asparagus.) But you could be looking forward to harvesting your own uber-local asparagus from your back yard in a year or two if you plant some asparagus crowns this spring.
Start with healthy crowns, purchased from your locally-owned independent garden center. Find a sunny part of the garden that is well-drained and won't be disturbed each year, and till the soil deeply. If drainage is poor, build a raised bed. Soil preparation is VERY important for perennial crops like asparagus, even more so than for annual crops that you harvest and replace each year.
Add compost or composted manure to add organic matter to the soil. Then dig a trench 8 to 12 inches deep and 12 inches wide. If you plan more than one row, space the rows 3 to 4 feet apart. Sprinkle in a complete fertilizer, mix with the loose soil in the bottom of the trench, then make a low mound of soil in the bottom of the trench with the enriched soil.
Space the crowns 15 inches apart on the mound, spreading the roots over the sides of the mound. Cover the crowns with loose soil about 2 inches deep. Water in well. As the shoots emerge, fill in around the shoots, but don't cover the growing tips. The trenches should end up filled to the soil level or just above if you don't have raised beds.
Don't cut any spears the first year. Keep the bed well-watered the first year, and mulch to keep the soil moist and the weeds down. Harvest lightly the second year, and as desired after that. Your own, fresh asparagus patch.