No verification for the idea that boxing day referred to the alms box, but it is as likely as other suggestions. Seems logical.

Turkey trivia-
The North American turkey (two species and several varieties) is billed as the bird used in Thanksgiving festivities by the Mayflower settlers, but the composition of the feast is unknown. Governor Bradford did write of sending hunters out for turkeys, ducks and geese, but not in connection with thanksgiving. The turkey also was being eaten in what is now the southwestern United States by Spanish colonists in this same time period.
The turkey had been domesticated by the native Mexicans and the Spaniards introduced it to Europe in 1519. The name came from turkeycock, a name for a Guinea-fowl, with which the American turkey was at first confused. It is not known whether Guinea-fowl or Am. turkeys are referred to in the "Turkies, carps etc." rhyme, although Am. turkeys were imported into England from Spain in 1524.

My reply to guest may be in error;- because of Dickens, in American minds goose always is associated with English festivities, Christmas or Thanksgiving. Many southern Americans associate ham with days of celebration, which seems to surprise some from other parts of the country.