My local friends get strawberry jam from Swanton Berry Farms, that tastes like fresh strawberries. And I usually make a pot of holiday mushrooms (recipe below). But those aren't math gifts...
I like getting used books for people I know will enjoy them, and I buy them through Better World Books whenever I can. (They get library rejects back into circulation, and contribute to literacy causes.)
The Cat In Numberland (4 to adult, review)
You Can Count on Monsters (4 to adult, review)
The Man Who Counted (4 to adult)
Quack and Count (1 to 5 years old)
Anno's Counting House (4 to 7 years old?)
How Hungry Are You? (4 to 10, reviews of last 3)
Keva or Kapla blocks (expensive)
These are only my most favorite math things...
most of a bottle of Burgundy wine
4 or 5 pounds of mushrooms
3 sticks of butter
3-5 bullion cubes or tablespoons of 'Better Than Bullion'
Wash the mushrooms. Only cut stems off if they're really hard. Put in a big pot with the rest. Cook for 8 hours. Your house will smell good, and they taste fabulous! (Don't forget the toothpicks.)