You don't have to be a walking encyclopedia, stuffed with facts about sizes, colors, preferred hemline lengths and pants-leg widths, in order to choose a gift mother will appreciate this year. You don't have to do any walking at all. This lesson is fright-free shopping comes from two businesses that will do the busy work of gathering, wrapping, even delivering the goods to mother, and all they ask of you are a few suggestions, such as mother's favorite scent, or what she likes to eat or read. They'll take it from there. f

Start with The Magic Filling (977-6647) or 963-2348), a gift service run by sisters-in-law Mindy Rubin and Sherry Ferdinand.After quizzing you about mother, they'll pack a basket or container with her favorite edibles, literature or other things that speak of her personality -- they say that in their business anything goes. The Magic Filling's baskets arrive festooned with banners and flags and a beribboned popcorn ball, which has become their trademark. They'll deliver anywhere by United Parcel Service (prices start at $15).

If Mother prefers being pampered with perfumed soaps, potpourris, colognes, or unusual jams, condiments and other "comestibles," give Crabtree & Evelyn a call. The store located in the Connecticut Connection (1101 Connecticut Ave. NW, 659-0099) will stock a special basket or tin from their delicacies. aIf mother is within walking distance of the shop, they'll deliver it free. Delivery to other areas in D.C. and to Montgomery County is an extra $2. Or they'll send it through the mail.