Amazing, Mary :-)
Crofter was someone who owned only a small area of land. Výminkář or výměnkář is an old expression, the word originates from the verb vymínit si - to stipulate. When a farmer passed his farm on his son, he stipulated in a contract, that the son has to let him live on the farm, give him some amount of grain, food or wood for free, let him keep hens or something like that. Basically, the old farmer retired and the son had to take care of him.