In the United Kingdom Peanut M&M's were known as Treets until 1990. Additionally, Toffee Treets were also available for some time. The chocolate versions were not introduced until the brand became M&M's. This was partly to do with the market dominance of the similar candy Nestlé Smarties which made competing under anything but a very high profile brand difficult, with the added risk of reducing sales of the existing Treets brand.
Treets
Ousted by M&Ms in the 80s. Came in three varieties - peanut (yellow bag), toffee (pale blue bag at some point) and chocolate (brown bag).
Near-spherical chocolate/nut/toffee lumps, "sealed in a crispy shell". The "cred" kids version of Poppets and such - very adult-type sweets in little cardboard boxes with a cereal-box-style opening at the top. Could be stored in the inside pocket of your suit without any risk of stains.
Many moons ago Mars used to make 'Treets' fro the UK market. They came in 2 varieties 'Peanut' and 'Chocolate'.
As the standardisation of markets took hold chocolate 'Treets' warped into 'Minstrels' with a no-melt coating and oblate spheroid shape.
Later 'M&M's arrived being smaller in shape than 'Treets' in the same two flavours but now with waxy coloured coatings. Their packet colours of yellow and brown were retained.
These days the closet you can get to the old 'Treets' are those found in 'Revels'.