The pivotal Hebrew term implied in that question is עבור (OBUR). More probably, this term was derived from עבר (OBR), ‘to pass’.
Some versions (for example, KJV, Darby, Webster, Young) translate this term suggesting the sense was “(some food) that is remained (passed away) (from the land)”, then, some old stuff to eat, like ‘old corn’. The emphasis, in this case, is on the concept of ‘what is passing on (away)’, ‘what is old’.
But, another sense was mentioned by Adam Clarke (Commentary on the Bible, ad locum): “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 […].” (granted, in the case of that-epoch-Israelites, they weren’t ‘cultivators’, but simply ‘gatherers’; in every case, the sense remains the same).
John Parkhurst wrote: “As a N[oun] עבור produce of the land, q[uaque] d[ie] [that is, ‘every day, daily], what passes or comes from it […].” Or, like the English-speaking-people of today, we may say, ‘to take pot luck (for meal)’.
Like you see, the emphasis, in this case, is on the concept of “what is passed (from the land to the people)”.
The LXX seems to back this conclusion, translating the Hebrew expression הארץ מעבור with σιτου της γης, ‘grain of the earth’, but also, ‘food of the earth’. It is useful to remember that the originating Greek verb of the term σιτου is σιτευω/σιτεω, that means – basically – to feed > to eat > to nourish > to make fat (in the analogous manner of the Hebrew term לחם, ‘bread’ < ‘food’).
The Jerome’s Vulgate has de frugibus terrae, ‘from the fruits of the earth (soil)’. It is interesting that frugalis derived from the word frugis (‘fruit’). What frugalis did mean? Cortelazzo-Zolli, ‘Dizionario Etimologico della lingua italiana’ (on the Italian lemma frugale, ‘frugal’ [vol. 2, p. 461]): “prob. ‘frugalis’ era chi viveva dei prodotti della terra’ (‘prob[ably], ‘frugalis’ was who lived from the earth products’).
I hope this is useful for you.