Used to wear the B2 pin to school as a kid :)

Found explanations for some, hope it helps:

A1 - Russian Soviet Red Star Pin

The Russian Store's collection of Soviet Era pins can be extraciting for a collector. Each of these authentic vintage pins was made in Russia before the collapse of the Soviet Union. This pin/badge has two prongs on the back. In order to attach it to the hat, gently bring the prongs together, insert folded prongs into a previously made hole on the hat, and then spread them apart underneath.

B2 - Red Oktyabryonok Star Pin

This metallic star pin features a likeness of Vladimir Lenin as a young boy on a pin worn by the Oktyabryonok - Little Octobrist. Oktyabryata were a youth organization for children between 7 and 9 years of age in the Soviet Union, the firs step to a Communist Porty. Every Little Oktyabryonok wore this star pin (badge) with the portrait of Vladimir Lenin (Ulyanov) in his childhood.

D2 - Russian Soviet Komsomol Pin

The Russian Store proudly presents our one of a kind collection of Soviet Era pins. Each of these authentic vintage pins was made in Russia before the collapse of the Soviet Union. They make the perfect addition to any historical and/or military collection. This pin was worn by the Komsomol Party, the Communist Union of Youth members in the USSR. It depicting Vladimir Lenin on on a red Russian flag. It says VLKSM, abbreviation for All-Union Leninist Young Communist League.