Meaningful inflation did in fact take hold in the U.S. economy after March 2021: headline CPI inflation climbed rapidly and peaked at about 9.1% year‑over‑year in June 2022, the highest rate in roughly four decades. (usinflationcalculator.com)

Over the same period, prices did rise broadly across commodities:

• Food and agricultural products: U.S. Bureau of Labor Statistics data show food prices were about 10% higher in 2022 than in 2021, a notably faster rise than typical. (officialdata.org) Globally, the UN FAO Food Price Index hit record highs; it had already jumped 28% in 2021 and then rose another ~14% in 2022, with cereals, meat, dairy and vegetable oils all reaching record or near‑record levels. (euronews.com)
• Broad commodity indices: Major diversified commodity benchmarks surged during the high‑inflation years. The S&P GSCI, a standard global commodity index, gained about 40% in 2021 and 26% in 2022, explicitly noted as strong performance in an “extremely hot inflation” environment. (spglobal.com) Bloomberg’s own commodity index (BCOM) also posted strong double‑digit positive returns in 2021 and 2022, tying those gains to rising inflation. (bloomberg.com)
• Metals: Industrial metals saw large broad‑based price increases: an index of core LME metals (copper, aluminium, nickel, zinc, lead, tin) rose about 32% in 2021 (after a 20% rise in 2020), with copper alone up roughly 25% that year, reflecting tight supply and strong post‑pandemic demand. (news.metal.com)

Given that (1) significant, sustained inflation materialized in the U.S. and (2) commodity prices—including food, agricultural goods, and industrial metals—rose broadly during that inflationary period, Friedberg’s conditional prediction about what would happen if meaningful inflation took hold matches the subsequent economic reality.