Do you mean the Tandy Hills Natural Area?

Here is a link that might be useful: Tandy Hills

It's great that they are trying to preserve some small remnants of those once-immense prairies in Texas. Of course, as a practical matter, 160 acres can't be kept 100% native. But if the invasive nonnatives can be minimized, it can be kept as native as possible.

Don't think this is the area you are talking about, but there is a blackland prairie remnant, never tilled, with a sign, in Arlington, south of I-20 on the east side of New York Avenue. Some routes to Waxahachie from Arlington go past that piece of land.

Yes, merrybookwyrm, that's it. Thank you! I'll have to take the New York exit next time and see if I can find it again. I was afraid it had been sold or taken in by the state for road expansion.