As you might have expected, the St. Louis Rams did add an interior lineman via undrafted free agency, Ohio State OG Bryant Browning. As with most undrafted free agents, don't look for Browning to compete for a starting job in training camp. He's a fairly raw prospect with limited upside.
Browning does possess prototypical size for an NFL guard at 6'4" 319 lbs. He did not get an invite to the Combine this year, and didn't get to fully participate in OSU's pro day, hence his draft status. All of which is sort of ironic since he played every game.
As a senior, Browning moved from right tackle inside to guard, which did put his name on the preseason Outland Trophy watch list. His size makes him a decent pass blocker on the inside, but his run blocking left a little room for improvement. He moved in from right tackle after struggling with speed rushers in college.