Addition to the few items people have suggested, e.g. soap, candies, chocolate, skin care products from the drug stores have been a big hit among my female friends/family -
Drug stores (pharmacie) are very easy to find. They are stores with green neon signs flashing. They're equivalent of the drug stores we have in the US that carry OTC drugs as well as skin care, personal hygiene, baby products.
Many of the french skin care products are of high quality natural ingredients with reasonable prices. Many of the "cult" products are of small packages and are very easy to bring home, e.g. lip balm, sun care products, homeopathic remedies, eye cream. If interested, just search "what to buy at french pharmacy". You'll easily find recommended lists.