Here's some stuff from Karen Laur, the texture artist at Valve, who, to my knowledge, made nearly all textures in HL.
http://rib.quakeroach.net/HLsource.zip
Created 3 years ago2021-01-24 13:37:18 UTC by Bruce
Most of them are in .PSD formatsI used these windows plugins;
oof i dont have Photoshop