Träd, Gräs & Stenar ("Trees, Grass and Stones") is a Swedish rock band formed in 1969, from previous incarnations Pärson Sound, International Harvester and Harvester. The group was one of the front acts of the Swedish progg scene, although noticeably less political than their contemporary counterparts. Their sound has been described as raw, psych rock jam, by the writer David Pescovitz, who also notes the band would invite their audiences to improvise and collaborate. Background. Pärson Sound, International Harvester and Harvester.
https://en.wikipedia.org/wiki/Tr%C3%A4d,_Gr%C3%A4s_%26_Stenar