Status of the wool of a sheep that comes from lineage that includes a goat, for the prohibition against wearing blends of wool and linen: Bechorot 17a per Rashi
Sitting on tough, non-warming shaatnez material: Beitzah 14b-15a
Salesmen of shaatnez may carry it on themselves without intention for benefit; more careful people dangle it from a pole: Pesachim 26b
Fooling another into sinning, in selling an item of clothing to a Nochri, where a Jew who buys it from him will not recognize the shaatnez: Pesachim 40b
A shaatnez donkey blanket: Pesachim 40b
Cushioning soles for shoes: Beitzah 15a
Small bags: Beitzah 15a
Other Issues
Tzitzit-Fringes remind a person of the prohibition against wearing mixtures of wool and linen: Menachot 43b
The punishment for wearing a mixed garment: Makkot 21a
Whether wearing such a mixed garment for an extended period of time, and/or through multiple warnings, is one violation or is many violations: Makkot 21a-b
To what degree one must remove a garment, to be liable anew when one puts it back on: Makkot 21b
Removing such a garment if one discovers it when in public: Berachot 19b
