Can I grow any plants in soil that is mostly clay?

What is your location?

I seem to think azaleas like clay, also hydrangeas will grow in most soils but change colour depending on soil type.

Living in southern Ontario all of my adult life, I've had nothing BUT clay conditions and never had a problem with anything!! Whenever we could do so, we would add some fine gravel and sand to try and loosen up the clay but most of the time, we never bothered as we had too large an area to deal with, therefore, it was too much work and costly. Our garden was included in a tour of the local Horticultural Society so I'm not kidding when I say we had no issues. My neighbor (same soil, obviously) had a very plentiful vegetable garden with, again, no problems whatsoever. The only thing that MIGHT not do so well is if you plant succulents. In that case, I would really advise amending the soil with whatever your local garden centre suggests. If you keep the succulents in say, one small specific area, it won't be too labour intensive or expensive to amend the soil as it's confined to one small area in the garden.

Just an added note ... if you are a lover of hydrangeas, because clay is alkaline, they will tend to produce pink blooms. Blue hydrangeas require acidic soil to maintain their color.

I live in a very heavy clay area. When planting I simply dig out my holes to size and throw out the clay soil. I then refill the hole with a mix of composted manure and Miracle Grow garden soil. Voila!!! You don't need to amend the whole yard; just where you need it. My plants are large and lush.

Using native plants as much as possible is what we do. They not only grow well but they are butterfly and bird friendly. Check out your local nurseryor agricultural extension website for varieties of plants and trees.