You may be talking about a jujube. I found one here in Denver last summer. Boy do the squirrels love it! It tastes a bit like a dry apple, but the pit can be easily chewed.

The leaves you describe don't sound like jujube leaves, but most jujube do have some thorns. I bought one this spring from Roger Meyer.

{{gwi:124439}}
This is the one I found last fall.

Do a search for Jujube and see if that's what you have.

Roger's website is still not finished, but you could get the contact information from here:

Here is a link that might be useful: Jujube Scionwood

Are you kidding me Squirrels eat every thing. They eat my pears, Apples, Figs even they eat my tomatos. Give me your address I will print it and distribute it to them.