Adam Clarke on Joshua 5:11

They did eat of the old corn of the land - The Hebrew word עבור abur, which we translate old corn, occurs only in this place in such a sense, if that sense be legitimate. The noun, though of doubtful signification, is evidently derived from עבר abar, to pass over, to go beyond; and here it may be translated simply the produce, that which passes from the land into the hands of the cultivator; or according to Cocceius, what passes from person to person in the way of traffic; hence bought corn, what they purchased from the inhabitants of the land.

On the morrow after the passover - That is, on the fifteenth day; for then the feast of unleavened bread began. But they could neither eat bread, nor parched corn, nor green ears, till the first-fruits of the harvest had been waved at the tabernacle; (see Lev 23:9, etc.); and therefore in this case we may suppose that the Israelites had offered a sheaf of the barley-harvest, the only grain that was then ripe, before they ate of the unleavened cakes and parched corn.