December 22, 1950: Put your hand inside the Snoopy head

Another somewhat pointless strip, Schulz must have been close to his deadline for some of these.  Snoopy is especially cute and puppet-like in this one however, especially in panel two, where we get a three-quarter perspective into his smiling mouth, and in panel four, where his eyes are winningly far apart.  As Snoopy became a much stranger creature later on, Schulz would lose the ability to draw him like this; Snoopy became a creature of imagination far more than a placeholder dog in a world of child jokes.

December 21, 1950: Tick tock

I've actually done this thing, with the hands, in real life.  I believe the joke here, which is a little subtle, is that Charlie Brown doesn't know how to tell time.

This strip is notable for, I believe, being the origins of Charlie Brown's distinctive zig-zag "Crayola" shirt.  (hangashore pointed it out in the Metafilter thread first.)

December 20, 1950: Don't you know, about the bird?

This rather straight-forward and pointless strip is notable for being the first appearance of a bird in Peanuts.  It looks quite different from Woodstock later on.

Woodstock originated as a hachling from a bird that built its nest on Snoopy's stomach as he lay atop his dog house.  The mother bird, if my memory holds up, looked fairly realistic, a lot like this one.

December 17, 1950: Shermy?!

At last, Shermy-the-mystery-boy is named!  Notice that all four of the original characters have an "ee" sound at the end of their name: Charlie, Shermy, Patty, Snoopy.  While I appreciate that Schulz always thought the name "Peanuts" for his strip was unnecessarily trivializing, with names like that I don't think he was helping his case.

But then, it was the 50s.

December 16, 1950: Hope you like dirt!

Mud pies, yum.  I was actually never under the impression that kids actually ate mud pies.  Note that Patty's mania for this dubious treat will in no way approach Violet's in coming months.

December 14, 1950: Upstairs, downstairs

A long-standing question for comic strip artists is, if the joke is wholly verbal, what do the characters do while they talk?  In this one, they walk up and down stairs, stairs that seem to exist to go nowhere.  Much later, Schulz will use the hang-out wall for this.  Bill Watterson, who has obviously read a lot of classic Peanuts, would adapt this into Calvin and Hobbes' wonderful sledding sequences.

December 8, 1950: Not receiving visitors

Unusual story construction in this one, basically two jokes in one four-panel strip, which is uncommon even today.  Dilbert pulls off two or more jokes sometimes in one weekday strip.

November 27, 1950: Everything is food, food, food

Snoopy's gluttony is established here for pretty much the first time.  Notice the "smile with tongue" he wears in the last frame.  This will often be used for Snoopy when he's looking at food, or is actually eating, in upcoming strips, almost to the point of cliche.

November 25, 1950: Improbable bedspread

Charlie Brown's bed appears for the first time. Look at how the grid pattern on it sort of slides off the bed.

In this strip Snoopy seems to be more obviously Charlie Brown's dog. It's hard to get a fix on his owner until the character relationships gel a bit.

November 22, 1950: But he's too young for school!

I bring this one up specifically because, next year, it's revealed that Charlie Brown is too young for school.  In fact, a previous strip established that he's only four at this time!  There's a sense in these early strips that the characters are not intended to have consistent stories, that they're more generalized stand-ins for types.  This may derive from the characters' origins as cartoons for the Saturday Evening Post.  No one asks who owns Thurber's dogs.