You are looking at a very gently handled vintage 1995 Limited Edition coffee mug from the

WESTERN MINNESOTA STEAM THRESHERS REUNION

in Rollag, Minnesota.  This commemorative WMSTR mug is dark blue in color with white specks and lettering, with an illustration of a Hart-Parr antique tractor.  Excellent condition with no chips, cracks, scratches or discoloration.  Made in England.