Present

Presents only fall while the Christmas season is running, and only from enemies the game counts as genuine threats. A monster has to be able to hurt you, carry more than a sliver of health, and drop coins when it dies. That rules out anything a statue spawned, everything belonging to the Old One's Army and the Lunar Events, winged Slimers, and Meteor Heads. The Present Mimic is tied to the same calendar, so hunting one outside December gets you nothing seasonal either.

Any event that floods the screen with qualifying enemies doubles as a present farm. A Solar Eclipse works well because the spawns are dense and nothing on its roster is disqualified. Early in a world the cheap option is repeat kills on the Eater of Worlds, since every segment is counted separately and the whole boss is a moving wall of them.

You open a Present from your inventory the way you open any grab bag, and the date on the calendar no longer matters once it is in your hands. A stack left over from last December opens perfectly well in July. Each one hands back a single Christmas item, with two exceptions. The Red Ryder comes out with ammunition to feed it, and each of the three vanity outfits arrives complete rather than a piece at a time.

Before the item was unified, presents came in blue, green and yellow. Those three stopped dropping long ago but were never stripped out of existing saves, so a chest untouched since then can still hold them. They behave exactly as they used to: a tiny pool of rewards built around candy cane blocks and the Snow Globe, no stacking, and no putting them on the floor.

The modern Present can be placed as furniture, and holding up or down while it is selected cycles through eight color schemes. None of them match the sprite you have been staring at in your inventory, the closest being a red box with a blue ribbon rather than the other way around. One of the eight is the exact coloring of the retired green variant.