Lepidium sativum.  A fast growing herb with a pleasant, peppery flavor. Curled Cresse produces an abundance of serrated, feathery green leaves that make a great addition to salads. Super easy to grow.  After bolting they will mature their seeds quickly and they can easily be gathered.
Cresse seeds can be sprouted in winter on a flat plate with only water. It takes ab0ut 7 days. The whole plant is edible. No need for soil, just scatter them in a little water on the plate, the easiest microgreen. The Wild Plum farmers rely on them to spice up their winter.  A 3g packet will make a nice plateful.
Outdoors it prefers moist soil and cooler weather. Best in spring and fall. The roots are shallow and delicate so take care in weeding.
Some seed saving tips from everwilde.com

Seed Saving: Cress reseeds itself readily if left alone after flowering, but the seeds can easily be gathered. Soon after blooming, the flowers will begin to fade and the seed pods will develop. Wait until most of the pods ripen to a light brown before picking the whole cluster of pods. Since the pods will split open and drop their seeds when fully ripe, watch them carefully. Spread the heads out in a protected location away from direct sunlight to dry fully, then thresh out the seed. Store curled cress seeds in a cool, dry place.

Cress, like others in its brassica family, maintains its seed vigor over many years.

A. 3g packet   $3.50
B.  7g     $7.00