Head to the center of town and rue du Général-Perrier, rue des Marchands, rue du Chapître, and the pedestrian rue de l'Aspic and rue de la Madeleine. A Sunday flea market runs from 8am to around 1pm in the parking lot of the Stade des Costières, site of most of the town's football (soccer) matches, adjacent to the southern edge of the boulevard périphérique that encircles Nîmes.
To appease your sweet tooth, go to just about any pastry shop in town and ask for the regional almond-based cookies called croquants villaret and caladons. They're great for a burst of energy or for souvenirs. One of the best purchases you can make, especially if you're not continuing east into Provence, is a santon. These figurines are sculpted into characters from Provençal country life and can be collected to create a unique country-French nativity scene. For a selection of santons in various sizes, visit the Boutique Provençale, 10 place de la Maison Carré (tel. 04-66-67-81-71).