This could be any toy that gives you a warm, fuzzy memory or one that you've been searching for since a family member or pet destroyed it.
To get the ball rolling let me tell you about something shocking that happened to Palitoy's end of the line Star Wars figures. I live in the Derbyshire area, Palitoy were based in Coalville and were the U.K distrubutors for Kenner.
Around 1985, when the Star Wars series fell out of favour for a little while, Palitoy had to get rid of the remaining stock so, they dumped them in a tip very close to where I live.
After one eventful weekend, that I didn't know was happening, the children at the local secondry school came in with pockets of classic Star Wars figures and they were trading them. Most of them were common robots like 21b and Ig88 but occasionally someone would come in with a Stormtrooper or a Han Solo hoth.
It got so bad that the teachers actually banned Star Wars. No one listened of course.