Based on the wiki, I couldn't find any record of the Patriots trading for a running back. Their backfield is currently Rhamondre Stevenson as the RB1 and TreVeyon Henderson as the RB2 — both were already on the roster (Stevenson was a holdover, Henderson was drafted in 2025) (from the Rhamondre Stevenson and TreVeyon Henderson pages).
The Patriots' notable trade this offseason was for A.J. Brown (WR), not a running back. If you're thinking of a specific rumor or trade, it might not be in the wiki yet.