TL;DR: The (complicated) claim for plastic is nearly true. The claim for steel and timber is false -- consumption of both of these commodities is climbing. For everything else, the claim is true -- consumption is flat or decreasing for electricity, copper, gold, fertilizer, water, cropland, and paper.
Almost true for plastic
For plastic, the claim is:
For decades prior to the Great Recession, plastics consumption in the US grew more than 50 percent faster than the overall economy did, but since 2009 the situation has reversed, with plastic use growing almost 15 percent slower than the economy as a whole.
The claim is very specific, but the data sources aren't provided (or even explained). What is meant by "plastics consumption"? What about "the overall economy"? There are several ways to look at each of these.
But, at the very least we should expect the trend in plastic production to change with respect to GDP.
The definitive source for plastics data in the U.S. seems to be The Resin Review. It's referenced by the EPA and several papers on plastic production trends, but unfortunately it's behind a paywall.
User @derobert suggested another source in the comments: FRED, the Federal Reserve Economic Database. Here's industrial plastic and rubber production in the U.S. vs GDP:
Here we can see that the claim is almost true. For nearly two decades (1983 to 2000), plastics production did outpace GDP growth. But in the decade before the recession it was slower than GDP, and since the recession it roughly matches GDP.
False for steel and timber
Steel -- on a post-recession rebound
From the U.S. Geological Survey National Minerals Information Center:
Timber -- on a post-recession rebound
Lumber is one processing step beyond timber, but the data was more complete than what the USGS had for "logs and wood chips," which would technically be closer to timber.
True for everything else
... except for "other physical building blocks of the economy" (though sales of Legos are declining, which is certainly a bad sign for childhood nostalgia, if not for the economy).
Copper -- essentially flat
Gold -- declining
Fertilizer -- essentially flat
Ibid. In this case, I'm assuming that fertilizer production tracks production of nitrogen fixed as ammonia.
Paper -- declining
Electricity -- essentially flat
From a recent U.S. Energy Information Agency blog post, "Record U.S. electricity generation in 2018 driven by record residential, commercial sales":
Water -- declining
From the USGS Trends in Water Use:
Cropland -- declining
From the USDA Economic Research Service Major Land Uses: