Cottons
I keep the DMC range of stranded threads.
A range of the DMC #5, #8 and #12.
Other cottons I have include:
Madeira Silk Thread
Scansilk Machine Embroidery thread
Kreinik Blending Filament
Pre-Blended Thread
House of Embroidery Perle and Rayon threads
Madeira Metallic Threads
Chameleon Threads - hand dyed rayon, perle, stranded cotton and stranded silk