San Francisco guitarist David Nelson, best known as a co-founder and longtime member of the New Riders of the Purple Sage, recently had surgery on his shoulder and is still recovering at home. The bad news is that Nelson will miss the David Nelson Band’s Get Well Harvest Tour, coming to the North Bay this week. The good news is that Vince Herman from Leftover Salmon joins the rest of Nelson’s longtime jam band to perform Nelson’s songs and select covers on Friday and Saturday, Nov. 18–19, at Terrapin Crossroads, 100 Yacht Club Drive, San Rafael. 8pm. $49. 415.524.2773.