This is a kind of passive called "Pasiva refleja". "Pasiva refleja" is the passive voice most used in Spanish. RAE explains it here. The way of forming it
Se + < transitive verb > + < nominal element >
The verb will be always conjugated in 3rd person. If the nominal element is singular it will be 3rd person singular, but if that nominal element is plural it will be 3rd person plural.
Se vende esa casa
Se venden esas casas
Se venden casas
Se venden (you can even omit the nominal element if it's implied)
If the "nominal element" has a determinant or is a pronoun it can be placed before:
Esa casa se vende
Esas casas se venden
Casas se venden* (Incorrect)
The sentences you provided also have the accusative pronoun "me". This element is used to "accuse" somebody of being "guilty" of that. In that case it is used "me" because you're referring to "Yo". As it is an indirect pronoun for a person/people you have to use this:
me (1st person, singular)
te (2nd person, singular)
le (3rd person, singular)
nos (1st person, plural)
os (2nd person, plural)
les (3rd person, plural)
So you' have for example this sentences:
Se me cayó (el libro).
Se te olvidó (nuestro aniversario).
Se te perdió (la mochicla).
In case you want to express explicitely who you're accusing to, you have to express it after the verb linking it with the preposition "a". You have to use the acusative pronoun before the verb even if you use this:
Se le cayó.
Se le cayó a él. (it emphasizes more than the previous)
Se te cayó a ti.
Se le cayó a Juan.
Se les olvidó a todos ellos.
Se les olvidó a todos ellos el cumpleaños.
Se les olvidó el cumpleaños a todos ellos.