Obviously a legume family member, but it's almost impossible without a little more info about the tree (size, leaf form, flowers, etc...)

They look a bit like pods from a mimosa tree, Albizia julibrissin, or some palo verde, but in your neck of the woods there are so many possibilities. Velvet mesquite pods are not as wide, nor as swollen around the seed, and a few other leguminous trees that come to mind have either much larger or smaller ones.

Look like mesquite beans to me. Color is right, the seeds appear to be very tight in the shell, and the size seems appropriate.

You're probably right nmgirl, seeing as you live in an area with mesquite.

But to me, they still look too wide and flattened, too swollen around the seeds, and not long enough to be mesquite. I just pulled out my stash of dried mesquite pods which average about 1/4 inch wide and nearly as thick, by 3 or 4 inches long, with 20 or so seeds very close together. This pic shows differently, with only about 7 seeds per pod. You're absolutely right that the color is correct, though, and I'm sure there could be a great deal of variation from tree to tree (although in my experience velvet mesquite in AZ has even longer pods)...
We'd know for sure in yayanator sent a pic of the trees themselves (in leaf).

I don't believe they are mesquite. I collected them in my plant biology class, and my teacher couldn't remember the name of the tree. He did say it wasn't mesquite. They also are not from a palo verde because I know what a palo verde is, and this tree wasn't one. I looked at pics of the Albizia julibrissin seed pods you mention, and I don't believe that is it either. I will try to take a picture of the tree next time I am at school.

If you picked these seeds up on the University of Arizona Campus in Tucson, Arizona, they keep a database of their many plants that have been plated there from around the world. They even have a carob tree there!