Ask Mr. Smarty Plants

The name sheepshire is associated with a couple of different sets of plants.  Two are in the genus Rumex—Rumex hastatulus (Heart-wing sorrel), a North American native plant, and Rumex acetosella (sheep sorrel), a European native—and the other plants referred to as sheepshire are all in the genus Oxalis.  (See a previous question and answer for a discussion on the species.)  I believe your plant is one of the species of Oxalis.   You don't say whether your plant is a potted plant or you dug it from the ground in Wyoming to carry to Oklahoma. The following list is of those with yellow flowers that are native to Wyoming:

Oxalis stricta (Common yellow oxalis) has yellow flowers and often has reddish or purplish leaves.

Oxalis dillenii (Slender yellow woodsorrel) has yellow flowers, but I could find no information suggesting it ever has red or purple leaves.

Oxalis corniculata (creeping woodsorrel) has yellow flowers and is often confused with O. stricta, but is more prostrate and has aboveground stolons that root and help spread the plant.  It's leaves are often more reddish than those of O. stricta.

Oxalis albicans (radishroot woodsorrel) has yellow flowers, but I could find no information suggesting it ever has red or purple leaves.   Here is another photo of O. albicans.

All of the species above are native to both Wyoming and Oklahoma. If yours is either O. stricta or O. corniculata and was taken from the ground in Wyoming, it should grow just fine in Oklahoma although it my be slightly more adapted to Wyoming's climate since that is where it was originally growing. 

If your plant is and always has been a potted plant, then I don't think it is a native species.  I suspect what you have is a non-native cultivated species such as Oxalis hedysaroides 'Rubra' (fire fern).  There are also non-natives with red/purple leaves and pink flowers, e.g., Oxalis triangularis (Purple shamrock).

You can read the article, "Care of Oxalis Plants", from eHow.com for general instructions for growing oxalis as a houseplant.  The article mentions that they (the houseplant ones, at least) tend to go into dormancy in the summertime.  Perhaps that is what is happening to yours.

You can check for seeds for the natives at a nursery that specializes in native plants in your area by searching in our National Suppliers Directory.