Burntridge Nursery is a little south of Raintree, but also sells this tree. Here's the blurb & the website:

YELLOWHORN - (Xanthoceras sorbifolia) Can be self fruitful, but not always. Unusual hardy tree native to northern China. Numerous pea sized nuts are produced in 2" seed capsules. White 1" flowers in spring. 1 ft. long compound leaves. Very ornamental, small tree. Leaves, flowers and nuts are edible. Useful for hedgerows, honey plants, wildlife. Zone 4-8.2-3 ft. $4.00 ea.

Here is a link that might be useful: Burntridge Nursery, WA

For any others who may run across this thread in this forum, here's more discussion from alexander's posting in another arena...

Here is a link that might be useful: yellowhorn thread

This is a nice small tree or shrub. I had planted this in my old backyard. Got a small one from Forest Farm, and it takes awhile to establish itself, so after maybe 5 yrs it was only 4 ft high w/ multi stems by the time we moved. The flowers were very nice, but best viewed up close. The foliage appeared light & delicate, fine textured. Mine was in part-sun, & it tended to lean - I think it might have grown better, and maybe faster if it had full sun. Not drought tolerant.
I'd love to try this one again!

I have been growing one of these in my climate for 4-5 years. I bougtht it as a infant from Raintree at 1 foot or so, one gallon. The indication is that it was a slow grower and boy, were they right about that. It hardly grew in the first two years although seemed healthy. Someone mentioned that they are not drought tolerent and I have to desagree because I live in the deserts of Southwest Utah and summer temps frequently get in the 100s and sometimes even in the teens although usually, not for more than a week. I do not and never have had the tree on regular water. I dump a gallon or two on it periodically and if I think if it, I run the hose for 15-20 minutes occasionally. It always stays green and is growing although slow. I have not really pruned it until this year and maybe, this did stimulate some growth as it has put on a 1.5-2' increase this season. I was not aware until I looked at these sites that it might not be self fertile or I might not have planted it as I have limited space and expected it to produce the nuts described. If I had known this, I would have probably have planted two in the same hole--not so practical at this point. I will probably just wait and see how it develops over the next year or two. I hope it produces nuts since that was my original motivation for planting it in the first place. By the way, I have run into similar info on other trees. I was thinking of planting a Pepper tree which aparently produces Sweschwan peppercorns. It was not indicated that this tree needed another polinisor. In the process of research, I found that it did and therefore, decided not to plant one afterall. Research your plant before deciding what you want to grow, especially with small yards. The info in catalogs is not always all the info., apparently.