Perhaps, at first, you might want to phone around top a few places such as Jewish old age homes or schools and ask them if they would have any use for them. If no one wants them they should be taken to the Genizah which is the place that unwanted (or worn out) items that have an inherent holiness to them are taken. I would imagine that most large Synagogues have a Genizah on their premises. I would suggest that perhaps you try phoning some of the larger communities and asking them where the Genizah is located so that you can take your Haggadahs there.