"Huckleberry" was commonly used in the 1800's in conjunction with "persimmon" as a small unit of measure. "I'm a huckleberry over your persimmon" meant "I'm just a bit better than you." As a result, "huckleberry" came to denote idiomatically two things. First, it denoted a small unit of measure, a "tad," as it were, and a person who was a huckleberry could be a small, unimportant person--usually expressed ironically in mock self-depreciation. The second and more common usage came to mean, in the words of the "Dictionary of American Slang: Second Supplemented Edition" (Crowell, 1975):
"A man; specif., the exact kind of man needed for a particular purpose. 1936: "Well, I'm your huckleberry, Mr. Haney." Tully, "Bruiser," 37. Since 1880, archaic.
The "Historical Dictionary of American Slang" which is a multivolume work, has about a third of a column of citations documenting this meaning all through the latter 19th century.
So "I'm your huckleberry" means "I'm just the man you're looking for!"
Now ain't that a daisy!
The "Daisy" comment is easier. In the late 19th century "daisy" was a common slang term for "the best in it's class." So for "daisy" just substitute "the best" and you'll have it. It was a short-lived idiom and doesn't seem to be popular much after 1890.
