Most works by Lewis Carroll are no longer protected by copyright, even if we apply the much longer terms of modern copyright: In most countries today copyright expires 70 years after the death of the author. Since Carroll died in 1898, this is long past. This also applies to the illustrations: E. Gertrude Thomson, the illustrator who lived longest, died in 1929, so her works, too, are no longer protected.
The only exception to this is with originally unpublished material. These texts may still be protected by copyright, depending on the date of publication and the laws you want or have to follow. For this reason I state the date of the earliest publication for these items, or at least the earliest publication I know of, even if I took it from some later source. Since I am German, I will follow German laws, which grant such texts a protection for 25 years after the first publication. I also assume that most printed works have been published by Carroll himself, especially those listed by Collingwood in his bibliography, but since even rare works where it is questionable whether they were published originally have been reprinted quite early, these should all have been published long enough ago anyway.
If your country protects originally unpublished works for a longer period, you will have to remove the respective texts before redistributing this collection. For your convenience the following list contains all texts published within the last 50 years for the first time (but note that in some countries the protection may last even longer):
1974: An Inconceivable Conversation; A Disputed Point in Logic. A Concrete Example; Life of Richard Hakluyt; Marriage Service; Number-Guessing; Logs of Nos.; Verses for Christmas Cards; Near Albury, so runs my lay; Square Poem
1975: Sidney Hamilton, Answers to Correspondents, The Village School, and Woes from The Rectory Magazine
1977: Symbolic Logic. Part II (parts already 1972); The Wasp in a Wig
1979: A Russian’s Day in England; To “Hallie”; My dear Christie; No, no! I cannot write a line; My First we call her when her belt is on; Alice dreamed one night; My first is a drink resembling wine; some of the Memoria Technica Verses
1981: Double Acrostic (for Agnes and Emily Hughes); O come to me at two today; If Ruth & you
1982: Charade (for Amy Hughes)
1994: some of the Memoria Technica Verses
1995: Little Red Riding Hood
1998: Dear Dolly, since I do not know
These dates are the earliest publication dates known to me, but it is likely that many texts have been published earlier, even much earlier. Take the Ligniad as an example: Most bibliographies will tell you it was first published in 1973, some in 1976. But if you dig a bit deeper, you will find several auction catalogues from earlier years, which reprint parts of the poem, and since each one reprints other parts, almost the whole poem had been published before. And if you dig really deep, you will come across an obscure magazine Eastbourne which had in its issue of Aug. 2, 1897 an article titled An Early MS. of Dodgson’s, and Entirely Unpublished which reprints the poem completely. This article was published on the death of Woodhouse, and I think it likely that similar articles appeared—more or less unnoticed—for other recipients of Carroll’s manuscript poems. The same is true for auction catalogues: They often reprint short manuscripts, sometimes even in facsimile, but aren’t recorded in bibliographies. So several of the above works are probably no longer protected even in countries with longer periods of protection.
The only part that is protected by copyright is this preface as well as the code used to generate the different files. You are allowed to distribute or otherwise use these (and thus the whole collection) under the license CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0/). If you want to re-use parts of the LaTeX code you may alternatively do so according to the terms of the usual LPPL (https://www.latex-project.org/lppl/). The code to build the files may also be used alternatively according to the terms of the MPL (https://mozilla.org/MPL/2.0/).
All code and data is available from Github: https://github.com/Schnark/lewis-carroll