Update: Thanks Leonora (a horticulturist from the UK) for comfirming that this flower is from Cassia corymbosa! To survive the winters in Kamloops where this was growing, I'm certain it must be taken into a heated greenhouse as their winters are much colder than mine & we can't grow it here.
Sure looks like a cassia flower to me but the circumstances is unusual. This was planted outdoors where the winters would easily & quickly kill it.
I have a knowledgeable gardening friend who was in Kamloops at the same timer. I'm going to email him & ask him what he thinks this is. I know of no other tree with similar yellow blossoms as this that's winter hardy in Kamloops, let alone where I am which is much warmer.