Learn Hardcore Spanish (Spain): Mi madre encontró el mapa en mi bolsillo y me lo devolvió. - My mother found the map in my pocket and gave it back to me.

me = to/for me (indirect object)
lo = it (the map), masculine singular direct object
Spanish places the indirect object pronoun before the direct object pronoun: me lo devolvió = she returned it to me.

Why isn’t it me devolvió lo or devolvióme lo?

With a conjugated verb, object pronouns go before the verb and stay together: me lo devolvió. You only attach them to the end with:

infinitives: devolvérmelo / me lo devolver
gerunds: devolviéndomelo / me lo está devolviendo
affirmative commands: Devuélvemelo.

When do we use se lo instead?

se replaces le/les when another third-person direct object pronoun (lo, la, los, las) follows, to avoid le lo. Examples:

Mi madre se lo devolvió a él. (= le lo → se lo)
Here we use me, so it stays me lo.

Why lo and not la or le?

lo agrees with the direct object’s gender/number: el mapa → lo.
la would be used for a feminine direct object: la pulsera → me la devolvió.
le is for indirect objects (to someone), not for replacing el mapa here.

Why is mapa masculine even though it ends in -a?

It’s one of several Greek-origin nouns in -ma that are masculine: el mapa, el problema, el programa, el tema, el clima, el sistema, el esquema, el poema, el drama.

Is the preterite the best tense in Spain? Could I say ha encontrado… me lo ha devuelto?

Both are possible. In Spain, the present perfect (ha encontrado/ha devuelto) is common for actions within the “today/this week” time frame. The preterite (encontró/devolvió) narrates a completed past event, and is standard everywhere (and preferred in much of Latin America).

Does encontró have a stem change like encuentra?

No. encontrar is stem-changing in the present (encuentra), but regular in the preterite: encontré, encontraste, encontró, etc.

Why are there accents on encontró and devolvió?

Third-person singular preterite typically carries an accent on the final vowel to mark stress: -ó (encontró), -ió (devolvió). Note that dio and vio (from dar and ver) do not take an accent.

Can I use de instead of en with bolsillo?

Encontró el mapa en mi bolsillo = she found it in my pocket (location).
de mi bolsillo means from/out of: La policía sacó el mapa de mi bolsillo = took it out of my pocket.

Why mi (no accent) and not mí?

mi (no accent) is the possessive adjective: mi bolsillo (my pocket).
mí (accent) is a stressed pronoun used after prepositions: para mí, a mí.

Is bolsillo the same as bolso or bolsa?

bolsillo = pocket (in clothing)
bolso = handbag/purse (Spain)
bolsa = bag (shopping/plastic bag)
cartera = wallet (Spain); in some places, purse/briefcase

Can I drop el mapa and just say Mi madre me lo devolvió?

Yes, if the referent is clear from context. The lo already tells us a masculine singular thing was returned.

Can I say Mi madre me devolvió el mapa instead?

Yes. Both Mi madre me devolvió el mapa and Mi madre me lo devolvió are correct. You can also use a relative clause: Mi madre me devolvió el mapa que encontró en mi bolsillo.

Why not just me lo dio?

dar = to give; devolver = to give back/return. me lo dio can be understood from context, but to express “gave it back,” devolvió is precise. me lo dio de vuelta is common in parts of Latin America; in Spain, me lo devolvió is more natural.

Can I add a mí for emphasis? Where does it go?

Yes, for emphasis or contrast:

A mí, mi madre me lo devolvió.
Mi madre me lo devolvió a mí. The clitic me remains; a mí adds emphasis.

What’s the difference between volver and devolver?

volver = to return/come back (intransitive): Mi madre volvió a casa.
devolver = to return something (transitive): Mi madre me devolvió el mapa. Don’t say volvió el mapa.

Why is it y and not e before me?

y becomes e only before words starting with an i sound (y inteligente → e inteligente). Since me starts with m, it stays y me.