Vintage Mail Order patterns are not from one specific company - they were syndicated through numerous publications and often come with the original mailing envelope for that added bit of historical ephemera. WeSewRetro has a bit of a soft spot for them and if you want to get all nerdy about it, you should read this.
Mail Order Patterns
1940s Vintage Mail Order Sewing Pattern - 1940s Dress Pattern, Mail Order 2934
1950s Vintage Mail Order Pattern - Dress & Bolero Sewing Pattern - Mail Order 4781
1950s Vintage Mail Order Sewing Pattern - Dress Pattern Patt-O-Rama 8198
1960s Vintage Sewing Pattern: Dropped Waist Dress. Grit 8277 Mail Order Pattern
1970s Vintage Mail Order Sewing Pattern - 1970s Dress Pattern, Marian Martin 9021