BROWNIES with ice cream is one of America's proudest traditions. But nothing is simple anymore. Which of three dozen flavors of ice cream? And now, to complicate matters further, which flavor of brownies? You see, Boston Brownies Co. is making 18 different kinds of brownies, from Kahlua chocolate chip caramel to rocky road. Apricot coconut to English toffee. Grand Marnier to Ameretto. And, of course, cheesecake brownies. And like Baskin-Robbins, the company's two Boston retail outlets let you taste a morsel before you buy.Look for the inevitable southward roll of the bandwagon as the idea gets around. And in the meantime, don't be surprised if your birthday is greeted with a Brownie Gram, a one-pound brownie bearing a message of up to 10 words ($12.95 including delivery, from Boston Brownies Co., 29 Chestnut St., Quincy, Mass. 02169). So far, only in fudge, but not a message to be ignored.

Prediction: The haute street food of tomorrow will be marinated mushrooms on a stick. We saw them in Boston's Quincy Market and noted that they are easy and inexpensive to produce, keep well, cost few calories and, like brownies, can be made in several flavors (hot pepper, oregano, garlic, lemon, you name it).

In the what-is-the-world-coming-to department, we record the conversation of some children of our acquaintance. They were boasting about the "really nice Gino's" they had visited. What was so special about it? They were most impressed that it had ketchup in bottles.

The most out-of-touch idea this season is the new Morton Salt cookbook, "Entertaining Ideas," which has nearly 50 pages of recipes for using salt, just when everybody else is trying to cut down salt intake. Along the way, Morton lets us know that -- not to be left behind by the ice cream and brownie people -- it makes six different varieties of salt.

And here is one for Morton's second edition. An Iowan (actually, he calls himself a "former Iowan") verifies the popularity in that state of rhubarb eaten raw, as we mentioned here several weeks ago. But unlike our last Iowan, who dipped hers in sugar as she ate it, Syd Kasper ate his Iowa rhubarb with salt. We promise to drop the subject of raw rhubarb, sugared or salted, here and now . . . unless, of course, we hear from an Iowan who eats raw rhubarb with mustard.

If you hurry -- to Baltimore, that is -- you can catch up with the first few blossoms of the summer festival season. Baltimore's showcase of Nations has 15 ethnic festivals left for the summer, days of food and entertainment and crafts, to be held in various locations around the city. The big festivals -- Italian, Jewish and Polish -- are later in the summer and usually draw over a million people each. But the smaller ones are said to be more authentic -- no hot dogs, for instance. June 6 and 7 is Lithuanian, in the charles center Plaza downtown, from 10:30 a.m. to 6:30 p.m. Sausages, tortes, dumplings and the like can be washed down with a spiced liquor called virtya. Then, June 13, the Scots, Irish, Welsh, Danes, Finns, Norwegians and Swedes join for a Celtic-Scandinavian festival, also from 10:30 a.m. to 6 p.m., this time in the Inner Harbor. Competing with the flavors of Harborplace will be their Swedish meatballs, scones, smoked salmon, anchovy sandwiches and bridies, this time to be washed down with ale and aquavit. Admission is free, music and dancing are plentiful, and the events continue rain or shine. For more information call (301) 752-8632.

When you need a strawberry in a hurry and there is nowhere to turn, the Produce Hotline can help you. A call -- (301)269-2184 -- brings three minutes of comforting advice: what the crop conditions have been this week, which fruits and vegetables are ripening and which are best buys, plus suggestions on how to find, buy, pick and store your Maryland produce.

It's not a field trip to the vineyards of Australia and the sunny slopes of Bordeaux, but your class notes will be every bit as exotic. The trip is merely to Mount Vernon College for Hamilton Mowbray's newest wine course, "Bargain-Hunting Wines Around the World," six Wednesday evenings from June 10 through July 15, 7:30 to 10 p.m. The fare is $55 plus a wine fee. For information call 331-3539.

The subject is not bargains but the event itself is a bargain at Bethesda's L'Academie de Cuisine. June 10 and 24 are Midday Gourmet classes, noon to 1:30 p.m., which serve you lunch and teach you how to make it, for $12, which is less than many a downtown lunch and tip, even without the lesson. Watch L'Academie's lunchtime schedules, for the classes are good buys, and some (but not all) of the menus are rather extravagant. For information call 986-9490.

Our favorite idea, today being the official launching of bathing suit season, is Prevention magazine's "Blindfold Diet." The magazine reported a Yale University psychologist's findings that seeing food makes some people hungry by causing them to secrete inordinate amounts of insulin. The logical conclusion, then, in a world where a fad diet is a rainbow leading from a pot belly to a pot of gold, is a see-no-evil diet plan. We forecast the three-piece bikini, one of them a blindfold.