The Almond Poppyseed Muffin is a muffin that contains both almonds and poppyseeds. The almond component can take the form of either almond flavoring, or slivers of almond on the top of the muffin, or both.
It isn't particularly informative for me to say that almond poppyseed muffins contain both almonds and poppyseeds, but what is informative is that this particular combination is one of the most popular flavors of muffin in the United States. Most grocery chains that have a fresh bakery will have almond poppyseed muffins, and for those who can't afford such quality, a number of companies make them prepackaged. Costco, the warehouse store, has infamous 12 packs of fatty delicious muffins, one-third of which will be Almond Poppyseed.
The particular appeal of the muffin is hard to describe, as are all matters of taste. Almonds and poppyseeds are both flavorful, but they are less of an instant crowd pleaser than, say the Chocolate Chocolate-Chip Muffin. Both are somewhat exotic tastes, being savory and almost musky in their flavor. If I was more inclined to the technicalities of culinary studies, I might be able to use more specific terms to describe their flavors, but they are both complex enough that their popularity as a breakfast staple seems odd.
It is true that poppyseeds contain morphine, enough to occasionally make a drug test go positive. It is also true that while other poppyseed containing confections may contain enough poppyseed to have clinical effects, this is probably not true of the common almond poppyseed muffin, where the sprinkling of seeds is as decorative as it is flavorful. But I do wonder if some atavistic connection is made in the mind between the presence of poppyseeds and the warm comfort of morphine. And furthermore, poppyseeds aren't the only poisonous ingredient present. Because almonds also are poisonous, containing non-trivial amounts of cyanide. Is greeting the day with an almond poppyseed muffin a way to commit symbolic euthanasia, taking morphine and cyanide together, even in vanishingly small quantities. When woken from peaceful sleep to start a busy day, the consumption of this toxin-laden pastry may be a way to insist on returning to the warm bosom of eternal rest, before the day continues.