The Phu Thai town of Renu Nakhon, 15km northwest of That Phanom, hosts a 35m-tall pink-and-white chedi that closely resembles the pre-1941 That Phanom stupa and is considered very holy. It's located in Wat That Renu temple, which also hosts a good textiles market with locally made fabrics (mostly indigo-dyed cotton) and clothes, as well as silk and cotton from Laos and elsewhere in Thailand.
There's no public transport. Túk-túk drivers in That Phanom ask for 300B round-trip.