How does Alice Munro use imagery in Walker Brothers Cowboy?

Imagery:

We leave my mother sewing under the dining-room light, making clothes for me against the opening of school. She has ripped up for this purpose an old suit and an old plaid wool dress of hers, and she has to cut and match very cleverly and also make me stand and turn for endless fittings, sweaty, itching from the hot wool, ungrateful.

The street is shaded, in some places, by maple trees whose roots have cracked and heaved the sidewalk and spread out like crocodiles into the bare yards.