Is this what you're looking for?

Here is a link that might be useful: yield chart

No, that's not it. I'm looking for something that says that for every square foot, square meter or acre that you plant in X crop, you should expect to get Y pounds (or kg) of crop.

If you can figure out average number of seeds per ounce and divide by square feet, you can use this chart:

Here is an excerpt:
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Here is a link that might be useful: Planting Calendar/Yield

I can't see how that helps (though thank you very much for trying!) I don't want to know how many pounds of seed I'm spreading per square foot - I want to know how many pounds of harvest per square foot I'm getting.

Now the linked table might be helpful if there was more information about how they figure out how long a row is needed per adult you're going to feed. They say in the footnotes that assumes 0.2 lb per serving, but it doesn't say how many servings they expect an adult to eat over a year. Or whether they're using the field row or hand cultivated measurements.

My question is, basically, if I plant potatoes in 20 square feet, then how many pounds of eating potatoes will I get? If I plant corn in 20 square feet, how many pounds of corn will I get? If I plant beans in 20 square feet, how many pounds of beans will I get? -- That sort of thing.

I've seen tables that say "these vegetables are the most prolific for their area" and I've seen the Square Foot Method sites that say you're guarenteed to get more yield per square foot using their method than any other. In the 40 or so gardening books I own, I have one (by Lois and Jim Hole) that gives a table with actual numbers. They don't cover very many vegetable types and I'd like very much to find another source to compare with theirs.

This one has pounds yield per 100'. Hope it helps!

Here is a link that might be useful: Planting Guide

Square Foot Method sites that say you're guaranteed to get more yield per square foot using their method than any other.

That's because you plant intensively with the SFG method and you literally can use 20% of the space for the same number of vegetables. It's not guaranteeing that your yield per plant will be greater. It's simply a more efficient use of garden space because you're not planting each variety in rows. For instance, you can plant 32 radishes in one long row, or you can plant 32 radishes in two square feet by planting 16 per one square foot.

I wouldn't take yield guides too literally, there are far too many variables. Think about what produce you purchase at the store each week, each month. How many cabbages do you eat each month? How many beans do you buy? You want to plant no more that what you're actually going to eat. So why plant an entire seed packet of cabbage when you only eat corned beef and cabbage for St. Pats?

What is it exactly that you are wanting to plant? Then we can help you better.

I'm not wanting to plant anything in particular, it's just that I'm trying to compare my garden yield with some sort of standard. Curiosity, mostly.

In the case of your radishes, perhaps the long row yields 4 pounds of radishes, each one 2 oz., in an area 96 inches long and 4 inches wide. That's 2.4 square feet. Perhaps the radishes planted very close together are also 2 oz each, so you're getting 4 pounds in less area.

Now on the flip side, perhaps those radishes crammed close together only average 1.5 oz each. Now you're getting 3 pounds per 2 square feet, or 1.5 lb/sq ft. Whereas a row planting gave 1.67 lb/sq ft.

I'm just pulling numbers out of the air - actually I figure SFM is a lot more efficient than row planting, but without any numbers to back it up, how can you tell? It all really comes down to what you enjoy and what works for you, but if people are selling a methodology on how efficient it is, then its efficiency should be demonstrable.

And in any case, I want to know if me growing 16 pounds of potatoes in 22.5 sq. ft. is average, above average or under average. I also want to know, as I plant things in the space that the potatoes occupied, what would give me the biggest bang for my buck. I can find supermarket prices, but I can't find yield information.

Like I said, this is mainly curiosity, because I've already planted half the potato area with beets and turnips. I think I'll plant some chard next to them.