Not sure when to use passé composé or imperfect tense

Hi  Vanessa,

La tête dans mon assiette 

is correct , mon is used because of the vowel regardless of the gender of the word 'assiette' which is feminine.

Take a look at the following question highlighting the same point - 

https://progress.lawlessfrench.com/questions/view/ton-assiette-ton-is-masculine-right-so-why-we-use-elle-in-the-example