I'm not a reconstructionist Heathen by any means; looking forward, I don't think I would be willing to change years' worth of my own traditions to be more historically accurate when more archaeological information comes to light. But since I'm currently building those traditions, I have an opportunity to create something that is reasonably akin to the religion my Pagan ancestors would have practiced. This is the perspective I'm coming from with my Anglo-Saxon religious calendar: it is based on research, but to flesh things out I've had to resort a bit to my own imagination.
If any of my readers are at all interested in Anglo-Saxon heathenry, I must recommend that you check out Englatheod.org; it's a wonderful resource where I've gotten many AS-specific tidbits of interest. One of these tidbits is an article on the Anglo-Saxon calendar year that goes into a great deal of detail on the possible ways the calendar may have looked and functioned. It is one of these possibilities on which I have based my own religious calendar, also using holidays attested by the venerable Bede in De Temporum Ratione, and a few traditional Asatru holidays that are not attested to in England, but which are important to me as a Heathen. Since the calendar is largely lunar, these dates will change year-to-year; but the following are for 2014.
February 14 - The Charming of the Plow (in which cakes are offered to the earth, a practice attested to by Bede for the month of Solmonað)
March 16 - Festival for Hreða (the full moon, and midpoint, of Hredmonað)
April 15 - Eostara, spring festival for the goddess Eostre (the full moon, and midpoint, of the month Eostara)
June 28 - Litha (placed on the new moon closest to the solstice; this would have been the day between two months called Before-Litha and After-Litha)
August 10 - Hlæfmæst (literally 'loaf-feast', on the full moon midpoint of Háligmonað)
September 9 - Freyfaxi (unattested in England, but an important Heathen harvest festival; I chose the full moon of September as it often lines up with other Freyfaxi celebrations)
October 8 - Winterfylleð (Winterfinding is the name of the month; given similar holidays attested in Norse sources, I have chosen to honor it with a feast-day, again on the full moon)
November 6 - Winternights (again, this is not a historical English celebration, but its importance in modern Heathenry brings me to celebrate it)
December 19 - Mōdraniht (I have chosen to celebrate this the night before the solstice, though there is some debate on where in December it should be celebrated)
December 20 - Solstice (I choose to honor Sunne on this day, though as far as I know this is historically unattested)
Jan 1 - Twelfthnight (this is attested in Norse sources, but given the history of the 'twelve days of Christmas' in England, I find it perfectly acceptable to extend the festive holiday season)