Boston — It's a small blessing, perhaps, but worth counting: Food prices actually have dropped a little. The price paid for food at the ''pre-retail'' or middleman level dipped 0.5 percent in November, according to figures just released by the US Bureau of Labor Statistics. That works out to an increase of only 1.5 percent annually - the lowest since 1976, when food dropped 2.5 percent on the producer price index.
If Boston is any indication, US shoppers already are returning from supermarkets with a little extra change. A local survey of 34 food items shows that a shopping trip costing $46.23 in November 1980 cost only $39.68 this November - a 14.2 percent drop. From dairy products to canned goods, the Boston Globe survey shows an across-the-board drop in almost all foods. Five pounds of sugar, which sold for $2.86 last year, is now $1.56. Name-brand hot dogs at $1. 82 a pound then are now $1.49. Margarine, mayonnaise, ground beef, orange juice, and many other items are down, while bread is up a few pennies and milk remained unchanged.
This year's record yields in some crops, and slackening meat consumption have helped weaken food prices. That's not good news for farmers, who are watching machinery and fertilizer costs and interest rates climb - but it could allow a little belt-loosening for consumers.
However, don't throw out the discount coupon box. There can be a big difference in the rate of change between prices at the intermediate stages and at the retail stage, says one Labor Department spokesman. ''A lot of other things come into play - such as salaries for retail clerks,'' he explains. In fact, the latest statistics on the retail prices for food - October 1981 - show a 4.7 percent increase since October 1980.
With the exception of fresh fruit, which typically increases in price at this time of year, food prices often dip in the late fall, when the harvest is in, livestock is taken to market, and supplies are generally high.
''I don't expect the oversupply situation to continue,'' the Labor Department spokesman says. Although meat (particularly pork) is overstocked, livestock producers can compensate quickly by cutting back herds to coax prices up.
''There's really not too much to drive retail prices up'' over the next few months, predicts Ralph Parlett, an economist with the US Department of Agriculture. He figures prices will be ''on the down side'' during 1982.