A gas turbine engine generally includes a fan and a core arranged in flow communication with one another.  Additionally, the core of the gas turbine engine general includes, in serial flow order, a compressor section, a combustion section, a turbine section, and an exhaust section.  In operation, air is provided from the fan to an inlet of the compressor section where one or more axial compressors progressively compress the air until it reaches the combustion section.  Fuel is mixed with the compressed air and burned within the combustion section to provide combustion gases.  The combustion gases are routed from the combustion section to the turbine section.  The flow of combustion gases through the turbine section drives the turbine section and is then routed through the exhaust section, e.g., to atmosphere. 
More commonly, non-traditional high temperature materials, such as ceramic matrix composite (CMC) materials, are being used for various components within gas turbine engines.  For example, because CMC materials can withstand relatively extreme temperatures, there is particular interest in replacing components within the flow path of the combustion gases with CMC materials.  In particular, rotor blades of the turbine section of the gas turbine engine are more commonly being formed of CMC materials. 
CMC turbine rotor blades generally are formed from a plurality of plies of CMC material.  Ideally, the plies utilize continuous CMC fibers, i.e., CMC fibers that are continuous along the length of the ply.  Because CMC materials typically are strongest in the direction of the CMC fiber, turbine rotor blades utilizing continuous CMC fiber plies can better withstand stresses during operation of the turbine. 
However, CMC blades utilizing continuous fiber plies often are attached to the turbine rotor disk through a pin and clevis type of attachment.  More specifically, a pin may be inserted into a pin hole in one side of the rotor disk, through a pin hole formed in the rotor blade, and then through a pin hole on the opposite side of the disk.  Typically, the pins have a round or circular cross-section, which have a line contact with the blade and, therefore, the contact, crush, and/or other stresses between the pin and blade may be undesirably high. 
Accordingly, an attachment mechanism for attaching CMC rotor blades to a rotor disk that avoids relying on the interlaminar capability of the CMC material would be useful.  Further, an attachment mechanism for attaching CMC rotor blades to a rotor disk that minimizes stresses between the attachment mechanism and the blade would be beneficial.  More particularly, a pin for attaching CMC rotor blades to a rotor disk such that a surface contact is provided between the pin and the blade would be advantageous.