My mother-in-law loves gardening as well, and we have always done well with getting her some plants and flowers that she doesn't have already. Some lovely garden furniture, decor, torches, lights etc. would also be nice.
There are many great gardening gifts that you can buy for people who loves gardening. You can get lawn ornaments, lanterns, or flower pots.
Some great gifts for experienced gardeners or beginners would be a collection of garden gloves, hand tools and a collection of vegetable seeds or flower seeds. Aerogardens are great for indoor gardening as well as starting seedlings. There are other gift ideas such as kneeling pads or garden stools that any gardener would appreciate.
Some really good gift ideas to give to your son for gardening are purchasing seed packs for different strains of plants and equipment for use outdoors.
There are many great gardening magazines for gardening enthusiasts that you may be interested in. Some great magazines include Garden Design, Organic Gardening, Urban Garden, Fine Gardening, and The American Gardener.
The best thing to put in a gift basket depends on the person who will be receiving the basket. If the person enjoys gardening, you might put flower bulbs or gardening gloves in the basket.
There are many great websites where you can get great garden gifts for your mother. Some of these websites include http://www.uncommongoods.com/home-garden/garden and http://www.redenvelope.com/home-gardening-gifts-rgrdn.
Some garden gift ideas that would fit nicely in the basket would be gardening gloves and a shovel. Other gift ideas could include a gardeners hoe tool, gardening hat, a garden kneeling pad, and a pruner.
Demeter is not mentioned by Hesiod when Pandora is given gifts.
That's great you want to start your own organic garden. There are several websites that have some great information regarding Organic gardening. My favorites are: organic gardening world dot com and smiling gardening dot com.
Cotton will work great for gardening if you don't deal with water.
You have a wide range of choices for a welcome gift. If you're not sure of your new neighbor's gardening skill, you might want to go with a dish garden or a potted bush that not only looks great "as is" but can be transferred to a garden later on.
Bookstores such as Barnes & Noble and Borders have great books on planting and gardening. Also, your local library will sure to have a variety of gardening books.