What type of tree is this?

I have a tree in my yard that has beautiful pink flowers on it that resemble a sweet pea. Can you help me to identify it? I have small ones popping up all over in my yard the past couple of years.

Thanks.
DebiLynne

Here are two close up pictures of the baby tree that is growing about 10 feet from the big tree. The red/yellow "down" on her is quite prickery. And the leaves are smoothe to the touch...not sticky.

DebiLynne

 

Maybe a pink-flowered cultivated variety of the black locust?

 

Locust (Robinia): Yes
Black locust (R. pseudoacacia): No

 

There's 3 or 4 species of Robinia with pink flowers, and hybrids between them; distinguishing them isn't too easy. It'll need much larger, more detailed photos, showing e.g. whether the shoots are downy or not, and also comment as to whether the foliage feels at all sticky or resinous.

 

If not an example of a wild species, pink-flowered specimens found in gardens may not match up with descriptions of hybrid cultivars - making exact identification pretty much impossible.